During the 1990s when Apple produced external CRT displays, they built DB-15 video ports into Macintosh computers. Product manuals of the time referred to the port as the “Macintosh video port” and in the later 1990s, the “Monitor port.”
An Apple Service Source document for the Power Macintosh/Server G3 Minitower shows the port in a diagram labeled as the “Monitor Port.”
I have three different versions of this adapter that allows a Macintosh with this DB-15 monitor port to be used with a “standard” VGA monitor. The three versions I have are platinum, clear, and black. The black example is unopened. All three designs have the Apple logo.