I've just checked the script here, and Gamma Canaris IV isn't mentioned. Here's the part where Gamma Canaris is mentioned:
- Whatever that thing is outside, he yanked us off course from the Enterprise. Now on course 98, mark 12, heading directly toward Gamma Canaris region. We've got to get Miss Hedford to the Enterprise.
Not Gamma Canaris IV!Edit
It's actually Gamma Canaris N, which is a tip-of-the-hat to the planet seen in TOS: "Metamorphosis". Although the name of the planet was not explicit (it was in the "Gamma Canaris region"), The infamous TNG chart, StarTrek.com and Trimble's Concordance all call it Gamma Canaris N , which is quite possibly from the script.
I suggest merging this with Gamma Canaris, and adding a background note to that page mentioning the N notation.