[Exim] help documentation error

I am reading the filters section of the documetation. and ran across this
area that i think im interested in


<start>
${lookup{<key>} <search type> {<file>} {<string1>} {<string2>}}

${lookup <search type> {<query>} {<string1>} {<string2>}}

These items specify data lookups in files and databases, as discussed in
chapter . The first form is used for single-key lookups, and the second is
used for query-style lookups. The <key>, <file>, and <query> strings are
expanded before use.

<end>
while I will go and search to find out which chapter its in. it goes to tell
me but doesnt