form_userptr.3x man page
set_form_userptr, form_userptr — associate application data with a form item
int set_form_userptr(FORM *form, void *userptr);
void* form_userptr(const FORM *form);
Every form and every form item has a field that can be used to hold application-specific data (that is, the form-driver code leaves it alone). These functions get and set the form user pointer field.
The function form_userptr returns a pointer (which may be NULL). It does not set errno.
The function set_form_userptr returns E_OK (success).
The header file <form.h> automatically includes the header file <curses.h>.
These routines emulate the System V forms library. They were not supported on Version 7 or BSD versions.
The user pointer is a void pointer. We chose not to leave it as a char pointer for SVr4 compatibility.
Juergen Pfeifer. Manual pages and adaptation for new curses by Eric S. Raymond.