termcap format question

[Richard L. Goerwitz]

I'm having a little trouble understanding how the curson addressing
capabilities are specified in /etc/termcap.  %d seems pretty clear,
as do %2, %3, and %.  I don't believe I am grasping how the following
escapes work:


	%+x
	%n
	%B
	%D

The manual seems to be telling me that %+x adds x to the valued spe-
cified.  X thus becomes the offset.  What sort of type checking is
done on x, though?  Are there size restrictions?  If I want to spe-
cify an offset of 1, say, can I write %+\001?  Do I use a character?
With %n, %B, and %D I just don't understand what sort of terminals
would need to use them and why.