Added several additional sections related to search and testing search.

Heuristics-for-testing-search.md

@@ -21,6 +21,16 @@ Possible sources of top online search terms include:
 * Top 25 Searches for 'last week': (likely to have more topical searches) https://en.wikipedia.org/wiki/Wikipedia:Top_25_Report
 * Lots of sources, including both the above: https://en.wikipedia.org/wiki/Wikipedia:Statistics 
 
+# Consistencies (inconsistencies) in search
+Kiwix has been available for many years, as have ZIM files. Over the years the ZIM file format has been extended and modified. So has the way Searching has been implemented. Some of the older software and older ZIM files may behave differently. At some point we may be able to provide a matrix of software and ZIM file formats and how the intersections behave in various ways, including searching and search results. For now, let's remember there are likely to be differences and note these as part of investigating ways to improve search and search results.
+
+# Comparative testing
+Generally, Search should be consistent across all Kiwix apps, servers and utilities. There may be valid reasons for some differences e.g. related to UX expectations, performance, etc.
+  
+Kiwix includes various command-line tools, one is `kiwix-search`, another `zimsearch`. We've decided to pick `kiwix-search` as the reference to test the core search capabilities.
+
+The version I'm currently using is from: http://download.kiwix.org/nightly/2017-12-17/kiwix_tools_linux64_2017-12-17.tar.gz
+
 # Unknown behaviours (yet)
 The following are unknown, at least from my perspective. Hopefully we will be able to clarify the expected/desired/actual behaviours for these soon.