Thanks - that's what I thought.

What I was unsure about was the exact behaviour of these modifiers. For instance, I assume the DEC modifier (not using dec2, dec3 etc) will read numeric characters for as long as they keep coming in. So 123ABC would read 123, 12AB would just read 12.

But what happens I wonder if there are no numeric characters? If I tell the PIC to wait until the string "foo" is seen, then read in a 3 digit value, but there is no three digit value present, will it just keep on waiting until there is?

This becomes an issue as when no fix is present, some of the NMEA fields collapse into ,,, with no numeric values to read in. Not that it really matters, as long as I can identify them as bogus!

so waiting for "foo", foo123 will read in 123. But fooabcde123 will do what I wonder? I guess the only way to find out is to try :-)