The name of the constant, as seen by the Perl code.

The type of the constant (IV, NV, etc.).

A C expression for the value of the constant, or a list of C expressions if the type is aggregate. Defaults to name if not given.

The C preprocessor macro to use in the #ifdef. Defaults to name and is primarily used if value is an enum. If a reference or an array is passed, then the first element is used in place of the #ifdef line, and the second element is used in place of the #endif. This allows preprocessor constructions such as:

#if defined (foo)
#if !defined (bar)
...
#endif
#endif

which are used to determine if a constant will be defined.

A macro of 1 signals that the constant is always defined, so the #if/#endif test is omitted.

Default value to use (instead of croaking with “your vendor has not defined . . . ) if the macro isn’t defined. Specifies a reference to an array with type followed by value(s).

C code to use before the assignment of the value of the constant. This allows you to use temporary variables to extract a value from part of a struct and return this as value. This C code is placed at the start of a block, so you can declare variables in it.

C code to place between the assignment of value (temporary) and the return from the function. This allows you to clear up anything in pre. Rarely needed.

Equivalents of pre and post for the default value.

Generated internally. Is 0 or undefined if name is 7-bit ASCII, no if the name is 8-bit (and so should match only if SvUTF8() is false), and yes if the name is utf8-encoded.