Modula-2 also makes available several built-in procedures and functions. In describing these, the following metavariables are used:

`a`- represents an
`ARRAY`

variable. `c`- represents a
`CHAR`

constant or variable. `i`- represents a variable or constant of integral type.
`m`- represents an identifier that belongs to a set. Generally used in the
same function with the metavariable
`s`. The type of`s`should be`SET OF`

`mtype`(where`mtype`is the type of`m`). `n`- represents a variable or constant of integral or floating-point type.
`r`- represents a variable or constant of floating-point type.
`t`- represents a type.
`v`- represents a variable.
`x`- represents a variable or constant of one of many types. See the explanation of the function for details.

All Modula-2 built-in procedures also return a result, described below.

`ABS(`

`n``)`

- Returns the absolute value of
`n`. `CAP(`

`c``)`

- If
`c`is a lower case letter, it returns its upper case equivalent, otherwise it returns its argument. `CHR(`

`i``)`

- Returns the character whose ordinal value is
`i`. `DEC(`

`v``)`

- Decrements the value in the variable
`v`by one. Returns the new value. `DEC(`

`v``,`

`i``)`

- Decrements the value in the variable
`v`by`i`. Returns the new value. `EXCL(`

`m``,`

`s``)`

- Removes the element
`m`from the set`s`. Returns the new set. `FLOAT(`

`i``)`

- Returns the floating point equivalent of the integer
`i`. `HIGH(`

`a``)`

- Returns the index of the last member of
`a`. `INC(`

`v``)`

- Increments the value in the variable
`v`by one. Returns the new value. `INC(`

`v``,`

`i``)`

- Increments the value in the variable
`v`by`i`. Returns the new value. `INCL(`

`m``,`

`s``)`

- Adds the element
`m`to the set`s`if it is not already there. Returns the new set. `MAX(`

`t``)`

- Returns the maximum value of the type
`t`. `MIN(`

`t``)`

- Returns the minimum value of the type
`t`. `ODD(`

`i``)`

- Returns boolean TRUE if
`i`is an odd number. `ORD(`

`x``)`

- Returns the ordinal value of its argument. For example, the ordinal
value of a character is its ascii value (on machines supporting
the ascii character set). The argument
`x`must be of an ordered type, which include integral, character and enumerated types. `SIZE(`

`x``)`

- Returns the size of its argument. The argument
`x`can be a variable or a type. `TRUNC(`

`r``)`

- Returns the integral part of
`r`. `TSIZE(`

`x``)`

- Returns the size of its argument. The argument
`x`can be a variable or a type. `VAL(`

`t``,`

`i``)`

- Returns the member of the type
`t`whose ordinal value is`i`.

Warning:Sets and their operations are not yet supported, so gdb treats the use of procedures`INCL`

and`EXCL`

as an error.