Testing to see if a file is ASCII

[geoff at ISM780.UUCP]

de at dcl-cs asks:
>             ... what the other values represent ?
> switch ((c | *f->_ptr << 8) & 0177777) {
>         case 0405:
>         case 0407: /*magic number*/
>         case 0410: /*magic number*/
>         case 0411:
>         case 0413: /*magic number*/
These other values are also magic numbers.  I suspect they're for pdp11
executables, but they might have other applications.
	0405    "Old overlay"
	0411    "Separate I&D"

	 Geoffrey Kimbrough -- Director of Dangerous Activities
	INTERACTIVE Systems Corporation, Santa Monica California.
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