The parsed files of the AAPCAppE are searchable with CorpusSearch at www.aapcappe.org (the “AAPCAppE web interface”). The AAPCAppE web interface links the output of queries done on the “parsed” part to the “audio-aligned” part, so that researchers can readily access the speech signal (and associated Praat textgrid) for the results of their parsing queries.
Because the AAPCAppE is a parsed corpus, and because the AAPCAppE web interface uses CorpusSearch for searching through the parsed files, the user has to write CorpusSearch queries, to query the corpus for structures of interest. The CorpusSearch queries can be input into the field that you see when you click on the “New Text Search” button. The CorpusSearch site (http://corpussearch.sourceforge.net/) explains how to write queries. So does this how-to by Beatrice Santorini and Joel Wallenberg: https://www.ling.upenn.edu/~beatrice/corpus-ling/digs13-2011/index.html.
**Note that you do not have to download CorpusSearch to use the AAPCAppE web interface; all you need to do is type your queries directly into the field that you see when you click on the “New Text Search” button**
And here is the syntactic annotation manual for the AAPCAppE:
(…which explains the annotation system used).
And finally, in case you are a beginner in need an introduction to parsed corpora, the first six pages of this article helps explain: