This section describes the message formats for the Function Management Interface (FMI). The message formats are presented in a language-independent notation. Details of the message format notation and key assumptions about the contents of the message formats are as follows:
The srci and desti fields in buffer headers are stored in the local format of the application that assigns them, since only the assigning application needs to interpret these values.
The startd and endd fields in elements are always stored in low-byte, high-byte orientation (the normal orientation of an Intel processor).
For non-LUA applications, startd will either be 1 (data starts in the byte after the trpad field), 10 (nine bytes of padding are included between the trpad field and the start of the data), or 13 (12 bytes of padding are included between the trpad field and the start of the data).
For LUA applications, startd is 4 (three bytes of padding between the trpad field and the start of the data) in the first element of a message and 13 (12 bytes of padding) in subsequent elements.
The extra bytes are used by the local node for additional header information; this avoids having to copy data into a new buffer when adding this information.