Is there a maximum line length when using the WRITE statement? (I'm considering a general surface matrix as output from a model)
If I recall correctly, for default (sequential formatted) files there is a small limit (I think 256 or 512 characters), but it can be overridden using RECL= specifier in OPEN. For other types (unformatted, binary) either there's no limit or it is quite huge (~2**31).
You don't say which compiler you're using, so I'll assume CVF. The Compaq Fortran Language Reference Manual has tables under the description of OPEN(RECL=) that spell this out. Default is 132 for formatted, max is 2**31-1.