The labeling problem of CAD, in mechanical paper, some labels have borders (that is, a square surrounds the numbers). What does this mean?

There is no special meaning! If so, unless the cartographer has any special intention!

Marked text with boxes is just a standard form.

You can find it in "Label-Label Style-"!

You can look at the pictures below!

For reference only, I hope I can help you! !