Typed code. Not tested. You'll have to verify it. You will have to have some understanding of what an "oid" is to use it. An "oid" is the name or location or ID of a given element in a given document.
# This sets the variable, root_o, to the oid of the root of the document.
root_o = oid_root()
# This fills an ACL array, array_of_oids_with_attr, of all the elements
# that have the attribute "hightlight" set equal to "yes".
highlight_count = oid_find_child_attrs($root_o, array_of_oids_with_attr, "highlight", "yes")
# This will loop through the array (if it contains anything)
for (i = 1 ; i <= $highlight_count ; i++) {
# your "work" code will have to go here
# oid_content(array_of_oids_with_attr[$i]) is the "handle" for each
# element found by oid_find_child_attrs() above
} # for
For lots more help (have I seen you there already, Lisa? I kind of think so ... oh well, just in case...), your best bet, if you haven't solved this or moved on already, is to join the Adepters mailing list where lots and lots of Arbortext users, admins, and developers hang out 24/7/365. Information on joining that list (as well as pointers to lots of other Arbortext resources) can be found here:
http://blog.single-sourcing.com/top-arbortext-resources
See also:
http://www.single-sourcing.com/company/social.html
Good luck!