I suppose I should have been slightly more specific when asking whether chars
should be signed or unsigned. I was aware of the ANSI definition of char but
what I was really asking was whether NetBSD makes any assumptions about which
you are using.

The answer to this appears to be that there are a lot of places in the NetBSD
binaries that assume signed chars are the default but this is because they
haven't been debugged properly on systems which assume unsigned chars rather
than because NetBSD is supposed to be compiled with a default of signed chars.

Many thanks to everyone who has replied.

Rob Black