Assembler language programs are expected to use the IEWBIND and IEWBUFF macros. Topics Coding the IEWBIND macro and IEWBIND function reference contain the details for coding the IEWBIND macro. Topic IEWBUFF - Binder API buffers interface assembler macro for generating and mapping data areas describes the coding details of the IEWBUFF macro.
The IEWBIND macro generates standard linkage code to transfer control to the binder, so register 13 must contain the address of an 18-word register save area.