V. The External Declaration
Reading edition
An external declaration is required for each nonstandard library procedure or procedure compiled separately from the calling program, whether in Algol, Fortran or CODAP. Standard Algol procedures are described in Section VI. Note that a CODAP subroutine must take account of the special structure of the Algol calling sequence as described in Appendix C or be treated as a Fortran subprogram. The use of Fortran subprograms is described in Appendix G.
The external declaration has one of the following forms:
external I1, ..., In real external I1, ..., In integer external I1, ..., In Boolean external I1, ..., In
where each Ik is an identifier and n is any positive integer. A type declarator preceding the declarator external signifies a function procedure having that type. Note that no information about parameters appears in an external declaration. See Appendix A for syntactical definition.
In the ALGO mode, LIB cards must be included in the job deck for nonstandard library routines, in addition to the external declarations. Details are found in Section VIII.