gdb allows you to express the constants of Modula-2 in the following ways:

- Integer constants are simply a sequence of digits. When used in an
expression, a constant is interpreted to be type-compatible with the
rest of the expression. Hexadecimal integers are specified by a
trailing ‘
`H`’, and octal integers by a trailing ‘`B`’. - Floating point constants appear as a sequence of digits, followed by a
decimal point and another sequence of digits. An optional exponent can
then be specified, in the form ‘
`E[+|-]`’, where ‘`nnn``[+|-]`’ is the desired exponent. All of the digits of the floating point constant must be valid decimal (base 10) digits.`nnn` - Character constants consist of a single character enclosed by a pair of
like quotes, either single (
`'`

) or double (`"`

). They may also be expressed by their ordinal value (their ascii value, usually) followed by a ‘`C`’. - String constants consist of a sequence of characters enclosed by a
pair of like quotes, either single (
`'`

) or double (`"`

). Escape sequences in the style of C are also allowed. See C and C`++`Constants, for a brief explanation of escape sequences. - Enumerated constants consist of an enumerated identifier.
- Boolean constants consist of the identifiers
`TRUE`

and`FALSE`

. - Pointer constants consist of integral values only.
- Set constants are not yet supported.