searchTerms This parameter will be set to the name attribute of the input element of your search form. e.g. if your form contains 
<input name="theseWords" type="text" />
then you should include 
&searchTerms=`theseWords`
in your snippet call (default: searchTerms i.e. looks in $_REQUEST['searchTerms'])
searchFields Template variables to search (default: pagetitle, longtitle, introtext, content). User defined template variables can be used.
searchExtractChars Maximum number of characters in extract (default: 200)
searchMaxDocs Maximum number of docs to list (if unset or zero all are listed)
searchMinLetters Shortest length of search terms to use (default: 3). Warning issued if shorter lengths used.
searchOutputList Output document list as unordered list (default: 1).
This means that you need not insert <ul> or <li> tags in custom templates. The <ul> will have id="search-result-list" and the <li>s will have class "search-result-item">
searchParents (v 1.3) Include only parts of the document tree with these parents (the parents are included in the search)
searchExcludeParents (v 1.3) Exclude parts of the document tree with these parents (the parents are also excluded from the search). Can be combined with but overrides searchParents.
mb_charset (v 1.3) Database connection character set. Defaults to UTF-8 which should be fine for most MODx installations.
searchPaginate Set to 1 to enable pagination (default: 0). For further details on configuring pagination if not using the default settings, see the comments at the top of the snippet.
searchStartTpl Template to output at the start.
Default as of v 1.3: 
<p class="search-info">
	[+search.finds+] document[+search.plural+] found containing [+search.terms+].
</p>
[+search.form+]
[+search.pagination+]
searchEndTpl Template to output at the end.
Default: 
[+search.pagination+]
tpl Template for individual documents.
Default: 
<h3>[+search.result_link+][+pagetitle+][+/link+]</h3>
[+search.terms_found+]
[+search.result_extract+]
searchNoResultTpl Template to output if no results found.
Default: 
<p id="search-no-results">No Results Found</p>
searchNoInputTpl Template to output if no input given.
Default: 
<p id="search-no-results">No search terms given.</p>
searchPlural Plural character(s) for templating; applies to [+search.plural+] placeholder. (Default: 's')