I saw this old Buick instructional video last week and it shared some interesting info.
https://www.youtube.com/watch?v=SqhjGs2zFLo
-The predetermined amount of grease is said to be 1/2 for the joint and 1/2 for the boot. I have always thought it's silly to put grease in the boot because doing so doesn't serve any lubrication purpose. Maybe the intent is to use that extra grease as a "dam" to minimize grease migration from the joint when the grease warms up during operation? I have always just put a heavy dose of grease in the joint to make sure it's well lubed throughout, plus a little bit extra for good measure, and left the boot dry.
-The line around the joint housing is a measuring point. You use that line to measure from the small end of the boot to the line to set the amount of boot compression. It's basically like setting the "air pressure" in the boot.
Here's the part where he demonstrates the measuring
https://youtu.be/SqhjGs2zFLo?t=1186
All told it's a pretty cool video from back in the 90s that gives a lot of basic but educational technical information on joint types (ours is a cross-groove type), boot types and some service/installation procedures.