Less interestingly, this is also a TLA
. As in ATP
, XTP (xanthine triphosphate) or 6-O-Methyl-weirdly-hypermodified-nucleotide triphoshate.
In some ways, this is similar to the use of 'sugar' to describe any CHO compound that can form a ring or conforms to certain other rules. Of course, as with any human defined set, there are exceptions. I just can't think of any at the moment...