P.WRIT - privileged file write.

iostat = p.writ( buffer, filecode, sector
                [, words, errfnc] );

buffer: is a pointer to the memory location from which the output should be written.
filecode: is the TSS filecode to be written to. This will either be one of TSS's filecode (e.g. #D) or a filecode returned by DRL JOUT.
sector: is the sector within the file where the write starts.
words: is the number of words to write. If omitted, "words" defaults to 320.
errfnc: is a function that will be called with a PRINTF style call if there is an I/O error while writing the disk. If omitted, it defaults to .ERROR, which will terminate the program.
iostat: is the negative of the major status from the write. A non-zero value is only returned if you supply an "errfnc" that does not terminate the program.

P.WRIT allows a privileged TSS program to write to a TSS filecode using DRL PDIO. The function is not available in batch.