Epidemic parotitis, or even only One thousand, occurs as programming language particularly powerful for building & managing big databases and especially text-based information. the database capability is tightly built into a language & is very real life to utilize for a coder since the representation is rather a elementary multiply subscripted array. These structures, globals around Epidemic parotitis nomenclature, come managed in lasting gear prefer disc drive. A patterns has super sophisticated techniques to handle caching, buffering, compression & sorting completely intrinsical to the language. Portability & standardization has been a historic priority across several iterations within operating systems & devices above the hanker history of Epidemic parotitis.

Epidemic parotitis is different from either either okay,-standard programing language which limit a computer programmer from doing anything unusual. Software engineer enjoy its do definitions & compact code. It has universally been super effective to program & line 3 text because of the taken nature and severity provided what complicated IDEs currently run for more languages. This is offset by its speed & flexibility within treating sustaining tasks that would stimulate problems under a relational database model. M has been known as a right-saved secret in the IT industry. This secrecy is historically because there are no trafficker got a heavy vested interest inside promoting & marketing Epidemic parotitis & a emphasis in the Epidemic parotitis community has been applications, non promoting the language.

History
Epidemic parotitis began life when a Kassachusetts General Hospital Utility Multi-Programming System, developed within Octo Barnett's carnal laboratory at Massachusetts General Hospital (MGH) in Boston during 1966 and 1967. the original Epidemic parotitis rules was repose on a spare DEC PDP-7.

Octo Barnett & Neil Pappalardo were too exposed using MGH's plans for the Hospital Datthe system, found a PDP-9 & began using Epidemic parotitis in the admissions period and laboratory line 2 text reportage. Epidemic parotitis is an interpreted language and incorporates a hierarchical database file system to standardize interaction by having a information. A origins of Epidemic parotitis may be traced from either Rand Corporation JOSS through BBN's TELCOMP and STRINGCOMP. A Epidemic parotitis team deliberately chose to write a freshly language by owning portability within mind. A second feature non widely supported inside operating systems of the era was multitasking, which was also built into Epidemic parotitis itself.

Epidemic parotitis was presently ported to the PDP-15 where it lived for some period. Developed in a government grant, Epidemic parotitis was called upon to become freed in the public domain (there is no protracted the requirement for grants), & was presently ported to the total of more systems including the popular PDP-8, the Data General Nova and the PDP-11. Word of Epidemic parotitis spread mostly through the medical community, & per early Seventies was inside far flung apply, typically existence locally limited for their have needs.

Per early 1970s there were many varied implementations of Epidemic parotitis in the range of devices platforms. A virtually all far flung existence DECs MUMPS-11 on the PDP-11 and Meditech's MIIS. Within 1972 various MUMPS users take in order to standardize a currently fractured language, creating a MUMPS Users Class action & MUMPS Development Committee (MDC). These efforts proved successful; the standard wwhen complete by 1974, & was approved, in September 15, 1977, as ANSI standard, X11.1-1997. At all about a equivalent instance DEC launched DSM-11 (Digital Standard MUMPS) for the PDP-11. This quickly dominated a market & became a information implementation of the period.

When you took a early 1980s a total of trafficker uprise to market MUMPS-depending platforms. Them big were Digital Equipment Corporation with their DSM (Digital Standard MUMPS) product, and InterSystems with their ISM (InterSystems M) product on VMS & UNIX, & M/11+ on the PDP-11 platform. More corporations that developed crucial Epidemic parotitis implementations were: Greystone Technology Corporation by owning the compiled version known as GT.M, DataTree Inc. by owning an Intel PC depending product known as DTM, Micronetics Project Corporation sustaining the line of merchandise known as MSM for UNIX & Intel PC platforms (late ported to IBM's VM operating formulas), & M-Spherical by using MGM the Mac OS depending product. DSM-11 was superseded by VAX/DSM for the VAX/VMS platform. This was so ported to the Alpha in two variants when DSM for OpenVMS, & when DSM for Ultrix.

This cycle as well saw a great deal of activity per MDC. A 2nd revision of the ANSI standard for MUMPS was (X11.One-1984) was approved in November 15, 1984. In November 11, 1990 the third revision of the ANSI standard (X11.1-1990) was approved. Inside 1992 this same standard wwhen likewise adopted as ISO standard 11756-1992. Around this period a apply of M instead title was sanctioned. In December 8, 1995 the fourth revision of the standard (X11.One-1995) was approved by ANSI, and by ISO around 1999 as ISO 11756-1999. the MDC finalised a farther revision to the standard around 1998 but this has never been presented to ANSI for approval.

By 2000, InterSystems had become a dominant streaming video player in a market by having the buy of many of the more players. Ab initio it acquired DataTree Inc. in the early 1990's. In December 30, 1995, a aquisition of the DSM business line from either DEC was [http://groups.google.com/group/comp.lang.mumps/msg/d4509328a7930487 announced]. InterSystems so began to consolidate these products into one line of merchandise, badging the babies in the total of platforms when OpenM. Within 1997 InterSystems completed this consolidation by launching a unified successor known as Caché. This was according to their Philosophical system product however by using a bit of influences from either a more products. A plus of Micronetics Project Corporatiin were likewise finally acquired by InterSystems on June 21, 1998.

Greystone Technology Corporation's GT.K product was sold to Sanchez Computer Associates Inc. (okay, a portion of Fidelity National Financial Inc.) in the mid Nineties. In [http://www.sanchez.com/news_2000/nr_001107.asp November 7, 2000] Sanchez mass produced GT.M for Linux available under a GPL license. GT.M continues to become available in VMS & UNIX platforms under the traditional license.

A recently implementation of Epidemic parotitis, freed within April 2002, is an MSM derivative known as M21 from either the Real Programs Company of Rugby, UK.

Veterans Administration
A Veterans Administration (now called a United States Department of Veterans Affairs) officially adopted MUMPS when a programing language to exist as utilized to implement an integrated laboratory / pharmacy / patient admission, tracking & discharge rules in the early Eighties. A original version, a Decentralized Hospital Programs (DHCP) was delivered early & under budget! DHCP has been day & night extended within a years since, and is available at there is no prices in source code under the Freedom of Information Act. Sequentially to implement DHCP a VA likewise wrote an average layer called FileMan in MUMPS to work as a database management formulas.

Now, DHCP is referred to as Veterans Health Information Systems and Technology Architecture (VistA). A [http://www.hardhats.org Hardhats.org] web site is the center for the international community of Aspect developers & users & likewise serves something of the equivalent work for Epidemic parotitis typically.

About a entire VA hospital formulas in the United States and the Indian Health Service, besides when major area of the Department of Defense hospital Body (Composite Health Care System (CHCS), different than a VA's for historical reasons) entirely however start a formulas for clinical track.

Other Industries
Epidemic parotitis as well gained the as a consequence in the fiscal sector, in that experience due to its very much higher performance in comparison traditional SQL depending systems. Given similar devices, multidimensional databases prefer Epidemic parotitis come generally astir sixfold sooner than SQL for transaction processing, making them ideal for on the net systems rather banking. It besides range from either when-expert to hundreds of days sooner in interrogation, by owning other complex interrogation universally favoring a multidimensional approach. It is besides particularly practiced at consult related information around more data places "for free",The project that takes an expensive JOaround operation in SQL systems.

As of 2005 most use of M is either in the form of Caché or GT.M. Caché, particularly is existence strongly marketed by InterSystems & is with profits around penetrating newly markets, like telecomms, in which high performance databases come the critical requirement.

Description
M is occasionally an interpreted language, and shares basic syntax by using virtually all common Sixties information processing languages, most notable people like COBOL, however Dr. Kevin O'Kane has produced the compiler for it too. Commands come used of these to the line by owning whitespace existence significant, & sorted into procedures (procedure) around the fashion similar to virtually all structured programming systems. Procedures come just strings, and so it may be well stored in the underlying datastore, meaning that no want for "stored procedures" when there exists within SQL – anything may be stored.

The notable curiosity of Epidemic parotitis syntax is that spaces come important: there are contexts where the pair of spaces is interpreted otherwise from either one space. Following, & unlike virtually all programing language, spaces just can not exist as inserted freely for readability, except inside comments.

The average Thousand procedure consists of many "blocks", from each one prevent separated by the label (called the tag inside M-speak) in the foremost column. vocation into the procedure by using there are no tag resolutions in the entire procedure existence start, whereas calling by having a tag skips thereto point. This allows coder to place interactional commands at a top of a procedure then tag a actual begin of a code itself, allowing for the procedure to exist as utilized two interactively & as a work to become known as from either more code (view the GRASS article for an example of an surrogate way an additional language deals using similar issues). These are non conceivable to define comm& line macro instruction inside Thousand rather GRASS, however these are conceivable to nature and severity any line of M code and execute it immediately, including function calls.

one independent difference between M & virtually all more languages is that M has sole a single information nature and severity, a string, which it invisibly converts into common information types like prices or even dates. Machine-driven conversion of this sort is green to numerous scripting programming languages, but is typically considered the bad tool for virtually all languages because it potty only too easy lead to mistakes that come hard to debug. around a experience of M this would exist when arduous to refrain from but, as the underlying datastore would develop in complexness whenever it got to treat by using different types. When your family may require, M includes the complete & right placed of string manipulation commands, sorted into libraries.

A key to the Thousand patterns is that everthing variables come automatically multi-dimensional. For example, this command:

Placed The="abc"

creates The variable A & sets its value to the string. A equivalent variable could so become utilized to hang on to extra principles:

Placed The(1,2)="def"

Might place a string def into "slot" (1,2). Slots can as well exist as intended by using strings:

Placed The("first_name")="Bob"
Placed The("last_name")="Dobbs"

making a variables utile informatiin places on their have. Note that this lesson too demonstrates an additional feature of M, that assignments into variables don't erase more references already there. This makes it easily to "build up" the complex variable, utilizing many assignments.

Thousand variables function around a similar fashion while sustaining more programing language, in this when a program exits, the value is wasted. M comes onto its have using its conception of globals, variables which are then automatically & invisibly stored to the datastore. Globals come out when normal variables using a caret character ahead of the title. Modifying a sooner lesson so:

Placed ^A("first_name")="Bob"
Placed ^A("last_name")="Dobbs"

might effect around the newly record existence created & inserted in the datastore.

1 difference between M & the traditional SQL model of a database is the "level" of the commands in the language. M occurs as general purpose language sustaining the datastore, whereas SQL occurs as language dedicated to database functions. This may healthy like the minor distinction, however these are rather significant to know it. E.g., SQL includes the lookup work:

Choose * From either user In which first_name prefer 'Bob%'

comes back the names of matching records. M has there is no tantamount "high level" command prefer Choose, instead a software engineer must construct a microscopic routine sequentially to collect higher the matching records returned from either its lower-level functions. It should likewise become noted that M doesn't include any dealing controls, a lot changes to globals happen instantly, & no logging in the basic models. Nor does M include any rather user-depending security.

For tons one reasons one of a usual Thousand software occurs as database management models, providing a lot of the classic ACID properties on top of the generic 1000 implementation. FileMan is of these such case. In the Nineties several one shells were adapted to supporting SQL, turning virtually all 1000 systems into SQL systems. Although a user can exist as "fooled" (to a few degree) into seeing a rules as a SQL database, a models yet retains a speed benefits of the K datastore (view following).

a side sympto1000 of the way M evolved is that the M rules includes fairly complete trend lines for multi-tasking, multi-user, multi-machine programming. A previous 2 features come nowadays commonplace in virtually all operating systems, but a in the future is however non cleanly supported by virtually all systems. To demonstrate a ease of multi-machine trend lines, assume:

Placed ^|DENVER|A("first_name")="Bob"
Placed ^|DENVER|A("last_name")="Dobbs"

which sets higher The when prior to, however this instance on the remote machine known as "DENVER". Thousand softwcome are so trivial to distribute above numbers of machines, the feature that is however hard in virtually all SQL systems. This trend lines besides mass produced it convenient to expose a equivalent kinda distribution in the SQL (& more) shells sustaining ease, & it's non rare for One thousand systems to exist as the better distributed SQL guide than the "real" SQL body.

A second have of M around extra recent days has been to produce object databases. By "flattening" objects into the string representation, prefer XML, M systems may be utilized to store objects. An 1000 program so converts back & forth between the "real" objects & a string representations under that, & is a cappella to run such sooner than similar object-relational mapping systems running above relational databases. This should become potential, in case M may be utilized to produce the SQL that's sooner than SQL, making an object database that does't necessitate conversion to & from either SQL in the midst is attached to exist as potentially sooner.

The MUMPS database
In the traditional relational model, datastores consist of the total of tables, every 1 holding records for even a bit of particular object (or "entity"). E.g., an location book application would occasionally contain tables for Humans, ADDRESSES & PHONE_NUMBERS. the tables consist of a total of fixed-width columns holding of these basic piece of information (such as "first_name"), & to each one record occurs as row.

Therearound lesson any row in ADDRESSES is "for" the particular row within Population. SQL doesn't read a conception of "ownership" all a same, & takes the user to collect this page back higher. SQL supports this across procedure, using the conception of the foreign key; copying a bit of unique bit of information uncovered in a Humans table into the Location table.

To re-produce one "real" record for a location book, a user must instruct a database to collect higher a row inside Population it is interested within, extract a key, so seek the ADDRESSES & PHONE_NUMBERS tables for all the rows containing this key.

A SQL syntax for joining tables may seem simpler to occasionally computer programmer but:

Pick out * from either Humans p, ADDRESSES the, PHONE_NUMBERS n In which p.id = the.person_id & p.id = north.person_id & p.first_name = "Bob"

Therein lesson the In which looks for all the a's & north's (addresses & telephone number) that develop a human's ID tag stored in the babies, but only for p's known as Bob.

This trivial case already takes trinity search within different tables to go to a information, which, when busy people will require, is very slow. Sequentially to improve performance, a database administrator might place an stock in heavy-searched columns, in that lesson a person_id columns. An stock consists of a column containing a information to exist as discovered, & the record total of the matching row in the table. This is a cause that tables come fixed breadth, & so that a database may easy figure out a physical location of a record given a location of the begin of the table, the length of any row, and the total of rows to omit. Forswearing this simplification, performance of the relational model would exist as unserviceable.

Thousand's datastore places lone a physical locations. This means that records may be of any length, positioned anywhere, & contain anything. Looking is does'nt needful to locate any record, the pointer directly thereto record is well retrieved & followed to the information within wonder. the physical information around an M is generally stored inside a hierarchical structure of strings, intended as an regulated tree. This will bring an additional benefit across a relational model, when empty cells don't choose higher room when it neutralise the fixed-length relational table. K databases come so little & supplementary space effective than relational information structures. A caching methods utilized allow multiple users to access a information at the same time. This means that multiple users inside a equivalent information structures might by their apply, increase a likelyhood that the information node existence sought is actually however in memory. inside an operational rules that has been run a patch, the cache hit ratio is all all about 85%, which means that just about 15% of the I/O reads may effect in an actual papuan. This is an additional cause for Epidemic parotitis' increased performance (less disk operations).

[Sorry, but this whole paragraph is wrong.](Sorry, however this is does'nt how come. Epidemic parotitis was sooner prior to & these are possibly sooner okay,.)

[Please replace the previous paragraph, with this][So why doesn't the relational model do the same thing? Actually, occasionally of a big relational databases actually wash relational structures behind the scenes. It had much of scalability away from this project vary. However it own non been respire to provide the logical schema to replenish their physical schema. Virtually all of the successful MUMPS-bases information management systems utilize the extremely dynamic ]

Thousand globals come, as a matter of fact, indexes. For each one node in the spherical contains the pointer to the information. A actual method of access to the information structure is left to the implementor. the pointer body via a node information is an abstraction which resolves to a string of information. Unlike a relational model, within which indexes come a favorite-purpose object involved as a necessary evil utilized in a select few search, under Epidemic parotitis, a information is accessed in the manner which makes the virtually all feel to the application. A nodes come character & a indexes from either a nodes to the actual information come never seen. These are because Epidemic parotitis occurs as logical binding like than a physical binding that makes the Epidemic parotitis information thus personal & clear. This is however a second understanding for Epidemic parotitis's telling error-period supportability likewise when platform independence.

[[Where did this come from?? It may be correct for a single application, but certainly not the general case.] This makes M systems particularly well suited to looking up related data, as in the example above. The equivalent M statement would be something more akin to:

SELECT * from PEOPLE p, ADDRESSES a, PHONE_NUMBERS n WHERE p.first_name = "Bob"

Related information can be stored directly in the index, in p.addresses for example. In this case no lookup is needed, PEOPLE can point directly to the addresses and phone numbers. ]

The biggest consequence of this internal representation is that database operations are economical (in both disk space and execution time as well as portability). MUMPS is extremely well suited to real world data, which is often 'sparse' (ie has missing fields). There is no penalty in storage space if a defined data value is not present. This is an extremely helpful feature in a clinical context.

It cannot be overemphasized that real-world applications really do make heavy and unlimited use of these persistent, disk-resident "global" arrays, which can be of gigabytes in size. This is a notable difference between M and other languages (e.g. Perl) which provide "dictionaries," "maps," or other string-indexed dynamic arrays which are RAM-resident and hence limited in capacity. The ability to access string-subscripted multi-dimensional arrays, and to freely add and delete new elements, is not a theoretical capability. It is how the MUMPS language is intended to be used. Surviving M implementations are the result of heavy marketplace competition which was largely based on the ability of vendors to provide efficient and robust implementations of these "globals."

MUMPS includes almost no operating system specific command syntax, very few file system interface commands, and no machine specific commands. (Idiomatic M applications store data within disk-resident globals; the fact that these globals reside in operating system files is invisible to the application code). It is thus quite portable. Additionally, database manipulation code is extremely brief. A MUMPS routine implementing a complex database interaction might be a page or two of code. The equivalent in a less high level language (C, Pascal, Fortran, ...) is likely to be an order of magnitude larger. Several studies done in the 1980s and 1990s contrasted M rapid applicaton development with other systems including COBOL and SQL based systems. The results, published in the journal M Computing provide support for the claim by M afficionados that M is a highly cost effective application programming tool.

Summary of key language features
This incomplete, informal sketch seeks to give programmers familiar with other languages a feeling for what M is like. Neither the language description and the descriptions of each feature are complete, and many significant features have been omitted for brevity. These notes reflect the language circa 1994.

Data types: one universal datatype, interpreted/converted to string, integer, or floating-point number as context requires. Like Visual BASIC "variant" type.

Booleans: In IF statements and other conditionals, any nonzero value is treated as True. a Declarations: NONE. Everything dynamically created on first reference.

Lines: important syntactic entities. Multiple statements per line are idiomatic. Scope of IF and FOR is "remainder of current line."

Case sensitivity: Commands and intrinsic functions are case-insensitive. Variable names and labels are case-sensitive. No specified meaning for upper vs. lower-case and no widely accepted conventions. Percent sign (%) is legal as first character of variables and labels.

Postconditionals: SET:N<10 A="FOO" sets A to "FOO" if N is less than 10; DO:N>100 PRINTERR performs PRINTERR if N is greater than 100. Provides a conditional whose scope is less than the full line.

Arrays: created dynamically, stored sparsely as B-trees, any number of subscripts, subscripts can be strings or integers. Always automatically stored in sorted order. $ORDER and $QUERY functions allow traversal.

for i=10000:1:12345 set sqtable(i)=i*i set address("Smith","Daniel")="dpbsmith@world.std.com"

Local arrays: names not beginning with caret; stored in process space; private to your process; expire when process terminates; available storage depends on partition size but is typically small (32K)

Global arrays: ^abc, ^def. Stored on disk, available to all processes, persist when process terminates. Very large globals (hundreds of megabytes) are practical and efficient. This is M's main "database" mechanism. Used instead of files for internal, machine-readable recordkeeping.

Indirection: in many contexts, @VBL can be used and effectively substitutes the contents of VBL into the statement. SET XYZ="ABC" SET @XYZ=123 sets the variable ABC to 123. SET SUBROU="REPORT" DO @SUBROU performs the subroutine named REPORT. Operational equivalent of "pointers" in other languages.

Piece function: Treats variables as broken into pieces by a separator. $PIECE(STRINGVAR,"^",3) means the "third caret-separated piece of STRINGVAR." Can appear as an assignment target. After

SET X="dpbsmith@world.std.com"

$PIECE("world.std.com",".",2) yields "std". SET $P(X,"@",1)="office" causes X to become "office@world.std.com".

Order function

Set stuff(6)="xyz",stuff(10)=26,stuff(15)=""

$Order(stuff("")) yields 6, $Order(stuff(6)) yields 10, $Order(stuff(8)) yields 10, $Order(stuff(10)) yields 15, $Order(stuff(15)) yields "".

Set i="" For Set i=$O(stuff(i)) Quit:i="" Write !,i,?10,stuff(i)

The argumentless For iterates until stopped by the Quit. Prints a table of i and stuff(i) where i is successively 6, 10, and 15.

Commands: may be abbreviated to the bolded characters, usually one letter in length, case-insensitive, with one space after a command unless otherwise noted. These are examples of commands, not showing the full syntax and capabilities.

BREAK Signal Debugging of current process CLOSE IOdevice Finish using the IO channel specified by local variable IOdevice, releasing it to be used by another job or process DO XYZ call subroutine at label XYZ in local routine DO PQR(arg1,arg2,arg3) call with parameter passing in local routine DO XYZ^ROU call subroutine at label XYZ in external routine named ROU DO PQR^ROU(arg1,arg2,arg3) call with parameter passing in external routine named ROU ELSE command1 command2 ... conditionally execute rest of line, on failure of last IF or timed read (note two spaces following ELSE) FOR command1 command2 ... repeat until a QUIT breaks you out (note two spaces following FOR) FOR i=1:2:100 command1 command2 ... counted iteration, from initial value i=1 until i is greater than 100 with step size of 2 FOR i=1,5,9,"A" command1 command2 ... listed iteration with i equal to each value in list GOTO entryreference unconditionally transfer control to a label in local or external routine HALT stop processing of this job, closing all IO channels and killing all local variables, and relinquishing all locks (note two spaces following HALT) HANG seconds temporarily stop processing of this job for the duration specified IF cnd command1 command2 ... conditionally execute rest of line JOB TAG^ROU start execution in a separate process, with an empty list of variables processsing will start at the specified tag and routine KILL variable return variable to "undefined" state, applies to local and global variables. LOCK namespace Establish ownership of a namespace to allow synchronization of multiple jobs or processes MERGE variable1=variable2 Copy entire array from variable2 into existing elements of variable1 NEW variable1,variable2... stack old local variables, create fresh variables with these names. fresh variables are in "undefined" state. Fresh variables are lost and old variables are restored on QUIT. OPEN IOdevice Start using the IO channel specified by local variable IOdevice, preventing it to from being used by another job or process QUIT return from current subroutine QUIT value return from programmed function READ "Prompt:",x on current I/O stream, first write "Prompt:", then read line into variable x SET a=22,NAME="Dan" store value in variable SET (c,d)=0 parallel variable assignment to more than one variable TCOMMIT finalize current database transaction (note two spaces after TCOMMIT) TRESTART restart the current database transaction (note two spaces after TSTART) TROLLBACK retry the current database transaction, rolling back all changes TSTART transid start a database transaction with a particular rollback identifier USE IOdevice switch current I/O stream to device identified by local variable IOdevice WRITE !,"x=",x output to current I/O stream. ! = new line XECUTE "set a=5 do xyz" execute arbitrary string data as M code

Operators: No precedence, executed left to right, parenthesize as desired. 2+3*10 yields 50.

+ - * / sum, difference, product, quotient \ integer division, 1234.9\10 yields 123 # modulo 1.5#1 yields .5 _ concatenation, "nice"_2_"use" → "nice2use" & ! ' logical and, logical or, logical not < > numeric less than, numeric greater than = string equality [ string contains substring. "ABCD"["BC" → 1 (true) ] string lexically follows. "Z"]"A" → 1 (true) ]] string sorts after. "1"]]"A"→ 0 (false) ? pattern match operator, (regular expression string matching)

Intrinsic (built-in) functions:

Important structural components of the language (not commonly found in other languages):

$DATA(V) tests if a V is defined (has data) or not, and if V is an array or not. $GET(variable) tests value of variable, and if not defined, returns empty string $ORDER, $QUERY traverse arrays in sorted order $ORDER(a("abc")) value v is the next subscript, following "abc", according to the M collating sequence, such that a(v) is defined. $PIECE(string,delimiter,position) see above $SELECT(c1:v1,c2:v2,1:v3) if c1 is true yields v1, else if c2 is true yields v2, otherwise yields v3 $STACK(stacklevel) return information in deeper stack levels $TEXT(FOO+3^PGM) returns text of source code at line FOO+3 in routine PGM

Convenience functions similar to library functions in other languages:

$ASCII, $CHAR text-to-ASCII-code and inverse $EXTRACT(string,5,10) characters 5 through 10 of string; may be assignment target $FIND(string,find,from) substring search $FNUMBER() floating point formatting including numeric commas $JUSTIFY() general string formatting with limited numeric $LENGTH(string) returns a count of the number of bytes in string $RANDOM(100) random number in range 0 to 99 inclusive $REVERSE(string) reverse the characters in the string $TRANSLATE("abcd","ab","AB") character substitution; yields "ABcd"

Intrinsic (built-in) variables: Intrinic variables

$DEVICE status variable for current device $ESTACK, $ECODE, $ETRAP error handling variables $HOROLOG gives current date and time as day offsets from January 1, 1841 and seconds since midnight. $IO, $PRINCIPAL the current and first I/O device for a job or process $JOB the unique identifier for the current job or process $KEY auxillary status information from previous READ command. $QUIT whether current subroutine was invoked as a function or subroutine. $STACK current depth of subroutine stack $STORAGE current amount of memory available to current job or process $SYSTEM the unique identifier of current system or domain of concurrent processes $TEST success and failure flag for most recent timeout or IF condition evaluation. $TLEVEL current database transaction depth $TRESTART count of restarts that have occurred on current database transaction. $X, $Y current Column and line number on current device

Relationships between MUMPS, Caché, MIIS, MAGIC, InterSystems and Meditech
Early development of MUMPS is credited to A. Neil Pappalardo and Octo Barnett of Massachusetts General Hospital.

MUMPS evolution took two major directions: MUMPS proper and MIIS. MUMPS became an ANSI and ISO-standard language, and has been available for nearly two decades from a number of vendors. Gradually, one vendor, InterSystems, came to dominate. The result is that as of 2004 commercial MUMPS is today primarily hidden as the foundation of the InterSystems-proprietary system, Caché. Caché is available for multiple operating systems, including OpenVMS, Sun Solaris, Linux, Microsoft Windows, Unix, and Mac OS X under several licenses, including no-cost non-commercial use. InterSystems does not sell applications itself, but supplies Caché and other development tools to companies which use them to build applications.

Independent of InterSystems is the GT.M implementation of MUMPS. It is supported commercially for many platforms such as OpenVMS, Sun Solaris, Microsoft Windows, Unix, and Mac OS X with the Linux version for x86 processors open source.

Another line of development was led by Pappalardo, founder of Meditech, a successful vendor of medical applications and complete medical data processing systems. Within Meditech, an early version of MUMPS evolved into a language named MIIS (Meditech Interactive Information System), and a successor named MAGIC (not to be confused with a different PC database product of the same name). In contrast to InterSystems business strategy, MIIS and MAGIC are used only within Meditech and are not marketed to outside application developers.

A GNU/GPL C/C++ based Mumps_compiler is available for Linux, Windows and Windows/Cygwin based systems that translates Mumps to C++. This package also includes a C++ Multidimensional_hierarchical_toolkit class library that provides a Mumps personality and data base access for C++ programs.

"MUMPS" vs. "M"
While of little interest to outsiders, this topic was and is contentious within the MUMPS/M community.

All of the following opinions can and have been supported by knowledgeable people at various times: The name became M in 1993 when the M Technology Association adopted it. The name became M on December 8th, 1995 with the approval of ANSI X11.1-1995 Both M and MUMPS are officially accepted names. M is only an "alternate name" or "nickname" for the language, and MUMPS is still the official name.

Some of the contention arose in response to strong advocacy for the name M on the part of one particular commercial interest, InterSystems, whose CEO disliked the name MUMPS and felt that it represented a serious marketing obstacle for InterSystems. Thus advocacy for the name M to some extent became identified as alignment with InterSystems. The dispute also reflected rivalry between organizations (the M Technology Association, the MUMPS development committee, the ANSI and ISO standards committee) as to who determines the "official" name of the language. Some writers have attempted to defuse the issue by referring to the language as M[UMPS], square brackets being the customary notation for optional syntax elements.

Since the M Technology Association dissolved in 2002 and the standards were administratively withdrawn, it can be argued that as of 2004 the language has no official standard and, therefore, no official name.

The December 31, 1840 epoch

In M, the current date and time is contained in a special system variable, $H (for "HOROLOG"). The format is a pair of integers separated by a comma, e.g. "54321,12345" The first number is the number of days since December 31st, 1840, i.e. day number 1 is January 1st, 1841; the second is the number of seconds since midnight.

The reason for this choice of epoch is a bit of MUMPS trivia that illustrates the degree to which the design of MUMPS was driven by practical considerations. James M. Poitras has written that he chose this epoch for the date and time routines in a package developed by his group at MGH in 1969: "I remembered reading of the oldest (one of the oldest?) U.S. citizen, a Civil War veteran, who was 121 years old at the time. Since I wanted to be able to represent dates in a Julian-type form so that age could be easily calculated and to be able to represent any birth date in the numeric range selected, I decided that a starting date in the early 1840s would be 'safe.' Since my algorithm worked most logically when every fourth year was a leap year, the first year was taken as 1841. The zero point was then December 31, 1840.... I wasn't party to the MDC negotiations, but I did explain the logic of my choice to members of the Committee."

(More colorful versions have circulated in the folklore, suggesting, for example, that December 30th, 1840 was the exact date of the first entry in the MGH records, but these appear to be legends).

For those who care about such things, $HOROLOG hit 60000 on April 10^th, 2005; will be 70000 on August 26^th, 2032; 80000 on January 12^th, 2060; 90000 on May 30^th, 2087; and 100000 on October 16^th, 2114.