Specifies the size of the RETURN-CODE special register and its alignment in memory.
Set to RTNCODE-SIZE"4" immediately by XOPEN.
Set to RTNCODE-SIZE"8" immediately by P64 (applies to UNIX environments only).
If a program calls a program with a smaller RETURN-CODE set, on return the value from the called program is in the lower bytes of the RETURN-CODE, with the other bytes undefined. For example, if a program with a 4-byte RETURN-CODE calls a program with a 2-byte RETURN-CODE, the lower two bytes of the 8-byte RETURN-CODE are set, while the content of the other bytes is undefined.
If a program calls a program with a larger RETURN-CODE set, on return the lower bytes of the value from the called program are in the RETURN-CODE, with the content of the upper bytes lost. For example, if a program with a 4-byte RETURN-CODE calls a program with an 8-byte RETURN-CODE, the lower four bytes of the 8-byte RETURN-CODE are set, while the content of the other bytes is lost.
For Windows environments
If a program with a four-byte RETURN-CODE calls a program with a two-byte RETURN-CODE, on return the value from the called program is in the lower two bytes of the four-byte RETURN-CODE. The content of the upper two bytes is undefined.
If a program with an eight-byte RETURN-CODE calls a program with a four-byte RETURN-CODE, on return the value from the called program is in the lower four bytes of the eight-byte RETURN-CODE. The content of the upper four bytes is undefined.
When one program calls another, it is not necessary that the size of their RETURN-CODE registers match. If the calling program's RETURN-CODE register is larger than the called program's RETURN-CODE register, then any remaining bytes the calling program's register are undefined. For example, if a program with a two-byte RETURN-CODE calls a program with a four-byte RETURN-CODE, on return the lower two bytes of the value from the called program are in the two-byte RETURN-CODE. The content of the upper two bytes is lost.
If the calling program's RETURN-CODE register is smaller than the called program's RETURN-CODE register, then any bytes that cannot fit into the calling program's register are lost. For example, if a program with a four-byte RETURN-CODE calls a program with a eight-byte RETURN-CODE, on return the lower four bytes of the value from the called program are in the four-byte RETURN-CODE. The content of the upper four bytes is lost.