It's nice to see a Fortran code this old factored and presented properly as a subroutine! Other legacy Fotran codes are not very modular (at least this has been my experience).
An example of really bad use of statement labels - the convention I was taught was to use 7000 and 8000 for input and output (format statements) and to use 6000 for goto's<p>Start at 6000 and go up in increments of 10 or 100 and to use 6999 for the last label in a routine.<p>so when you wanted to exist a subroutine or function you would use GOTO 6999.