In “Examples of Using External Calls”, reorder prototypes to match order in the header

In “gtmxc_types.h”, Note about 1 MiB limit on strings

In “Using External Calls”, Add null address and negative length handling

In “Using External Calls”, added SIGSAFE keyword

In “Pre-allocation of Output Parameters”, specify that when an external call exceeds its specified preallocation (gtm_string_t * or gtm_char_t * output), GT.M produces an EXCEEDSPREALLOC error.

In “Rules to Follow in Call-Ins”, specify that using gtm_malloc is mandatory to allocate returns of pointer types to prevent memory leaks.

In “Nested Call-Ins”, tweak ZGOTO description for GTMCI behavior

In “Building Standalone Programs”, removed instructions for platforms that are no longer supported.

In “Creating a Shareable Library”, removed examples for currently unsupported platforms.

In “Using External Calls”, removed Tru64 and fixed formatting

In “gtmxc_types.h”, removed Tru64

In “Relevant files for Call-Ins”, removed HP-UX

In “Access to Non-M Routines”, added information about the external call arguments that do not specify a value and corrected the examples.

In “Using External Calls”, added a note about how arguments that do not specify a value translate to default values in C.

Improved the description of the “Pre-allocation of Output Parameters” section.

In “Rules to Follow in Call-Ins”, added a recommendation to not mix GT.M device input using read() system service with bufferred input services in fgets() family.

Added a section called “Type Limits for Call-ins and Call-outs”.