Fortran (or rather, ForTran or even FORTRAN, as this goes back to ye goode olde punched cardes dayes) way of saying ">". Using some weird nonalphanumeric symbol (">") for saying "Greater Than" would have been inadvisable. Especially since EBCDIC seems to like to put it at character 4C or 6E or almost anywhere else. Not to mention the fact that many card punches, terminals and other output devices would have been unable to display such a strange character.
Instead, the abbreviation "GT" was selected. But whitespace is insignificant in Fortran! Saying "I GT 0" would have been exactly like saying "IGT0", a variable (of implicit INTEGER type). Adding dots at each side makes it unambiguous, spaces or no spaces.
A remnant of this happy tale lives today in the Perl programming language: alphanumeric comparison uses the "gt" abbreviation. The dots, however, are long-gone -- Fortran allows the programmer to use ">".