Example 1: A reader of the printed journal often finds items of interest in Section H.2 on International Migration. A search using "International Migration" in the subject field and 1997 in the year field yields 457 citations that have appeared under this heading at that time.
Example 2: You are interested in Machine-Readable Data Files, which appear in section T of the journal. You note that we use the abbreviation MRDF. Typing "MRDF" in the subject field yields 395 hits. You can obtain exactly the same result typing "machine-readable data", with or without the hyphen.
Example 3: A student prepares to write a dissertation on child mortality in Africa. Typing "child mortality" in the subject field and "Africa" in the region field, she gets 219 hits. Adding the word "trends" in the subject field yields one paper on Zaire. Typing "differentials" instead of "trends" yields no hits, but the engine explains that there are no entries under "differentials". Shortening the word to "diff" yields 76 hits (the actual thesaurus terms used are "differential fertility" and "differential mortality").
Example 4: You are interested in recent work on the evaluation of family planning programs. Typing "family planning evaluation" in the subject field and 1990 to 99 in the year field yields 571 hits (the actual thesaurus term used is "family planning program evaluation", but you don't need to type all four words to find it).
Example 5: You look up "AIDS" and get only two hits. A quick look at the online thesaurus shows that the relevant entries are coded under "acquired immunodeficiency syndrome". Searching under these words yields 630 hits.