Format of DOS-11 magnetic tape header records:

	.rad50	/fn1fn2/	;1st 6 letters of filename
	.rad50	/ext/		;3-letter extension
	.byte	proj,prog	;ppn (display it in octal)
	.word	prot		;protection code, usually <233> octal
	.word	date		;date: (year-1970.)*1000.+(day within year)
	.rad50	/fn3/		;[optional] letters 7::9 of filename

Length=14. bytes (or 12. if no fn3, like in actual DOS/BATCH)