CouchDB wants its fancy startkey and endkey values properly escaped. So that means I have to look up ‘[' and ']‘ and so on for their hexadecimal equivalents. I usually turn to this super useful page, even though it is way down on the search results. The others look like spam websites.
So, tune your linkages to http://web.cs.mun.ca/~michael/c/ascii-table.html
Update: or as that anonymous comment says below, man 7 ascii