Another reason to use first-last instead of top-bottom references:
In i18n (an OpenACS project goal), when using UTF-8 or greater, some writing directions are top-to-bottom (vertical rendering) as well as right-to-left and left-to-right. With vertical rendering, the semantics top-bottom inaccurately reflect the page positions (left side, right side). Using first-last or begin-end etc. more accurately describe the template "position" and avoids confusion.
comment: My use of "popular" in the previous message is relative to current Western practices. Chinese is currently the most popular language on the planet. The template labeling could become a major issue if a small segment of the population fluent in Chinese start using OpenACS --a scalable solution for large online communities. Let's prepare for it ahead of time, eh? ;)