FORMAT specificationsTo support legacy codes, GNU Fortran allows the comma separator to be omitted immediately before and after character string edit descriptors in FORMAT statements.
PRINT 10, 2, 3
10 FORMAT ('FOO='I1' BAR='I2)
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https://gcc.gnu.org/onlinedocs/gcc-4.9.3/gfortran/Commas-in-FORMAT-specifications.html