Commentary for Gittin 8:18

"We learned in the mishna: One who brings a bill of divorce from one region to another region within a country overseas" - And from the first part of the Mishna "One who brings a bill of divorce from a country overseas" implies specifically from a country overseas to the land of Israel. It is not possible to apply [this rule (of saying it was written and signed before me)] that really in the same country overseas one also needs [to say it was written and signed before me]. This [example (of one who brings a bill of divorce from a country overseas)] was taken to exclude Rekem and Heger [from the rule of saying it was written and signed before me].