<<.from-version "5.1.18">> The search filter operator was significantly enhanced in 5.1.18. Earlier versions do not support the extended syntax and therefore do not permit searching multiple fields, or the ''literal'' or ''casesensitive'' options.
* Search mode - the first to be set of the following flags determines the type of search that is performed:
** ''literal'': considers the search string to be a literal string, and requires an exact match
** ''whitespace'': considers the search string to be a literal string, but will consider all runs of whitespace to be equivalent to a single space. Thus `A B` matches `A B`
** ''regexp'': treats the search string as a regular expression. Note that the ''regexp'' option obviates the need for the older <<.olink regexp>> operator.
** ''words'': (the default) treats the search string as a list of tokens separated by whitespace, and matches if all of the tokens appear in the string (regardless of ordering and whether there is other text in between)
* ''casesensitive'': if present, this flag forces a case-sensitive match, where upper and lower case letters are considered different. By default, upper and lower case letters are considered identical for matching purposes.