Each drawing can have a tag. You can use tags to group drawings thematically, e.g. different tags for borders, freighter routes, and enemy sightings. By default, all drawings are displayed, but you can filter display to show just one tag.

A tag can be a number or string (technically: an atom).

Setting Drawing Tags

You can choose the tag for a new drawing using T on the Drawing dialog.

You can change a drawing's tag using T on the starchart.

Both dialogs will let you enter a new tag, or choose an existing one from a list. When changing an existing line's tag, you can use AltA to change the tag of all adjacent lines as well.

Filtering Drawings

You can filter tags using AltF on the starchart. The dialog will let you select an existing tag and then display just that. Press AltF again to turn off the filter.

Reference

Keys:
T from starchart and Drawing dialog; AltF from starchart