Any syntax of HREF attribute is followed by Phpdig. PhpDig don't go out the root site you define for the indexing. Spidering depth is choosen by user. All html content is listed, both static and dynamic pages. Lone numbers are not inded, but those included in words.
Underscores make part of a word.
Occurences of a word in a document is saved. Words in the title can have a more important weight in ranking results. PhpDig can't perform an exact expression search. It doesn't matter for the search queries. Spidering and indexing is a bit slow.