VMS Help CC, Language topics, Storage Class Modifiers, __inline  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  The __inline modifier marks a function for inline expansion.  Using
  __inline on a function definition and prototype tells the compiler
  that it can substitute the code within the function definition for
  every call to that function.  Substitution occurs at the discretion
  of the compiler.  The __inline storage-class specifier has the same
  effect as the #pragma inline preprocessor directive, except that
  the latter attempts to provide inline expansion for all functions
  in a translation unit, rather than for selected functions.

  Syntax:

       __inline [type] function_definition