We have a custom-coordinate-system tag with 40 questions. It does not have a tag wiki or even an excerpt to guide us in its usage.
We also have a coordinate-system tag with 4,557 questions and of those 609 questions include the word "custom".
Do we need the custom-coordinate-system tag?
In Using/synonymizing/merging [coordinate-system] and [projection] tags? the community reached some consensus around reducing the number of tags related to coordinate systems.
I think the custom-coordinate-system tag is another one which should be made a synonym of coordinate-system.
Even though the topic of creating custom coordinate systems is more complex than using supplied coordinate systems it seems to me that it will be simple, and reasonable, to make them synonyms.
The alternative would be to retag many of the 586 coordinate system questions wich include the word "custom" but have not been tagged as involving custom coordinate systems.
