Docs: more detail on lookup keys

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index ed5b06a2dc2bd3a28c9fe2b2b3aa18fe75f76733..36ed7ca092f0b8074fba1f652c4bdfacf6614002 100644 (file)
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -6755,6 +6755,9 @@ domains = ${lookup{$sender_host_address}lsearch{/some/file}}
 domains = lsearch;/some/file
 .endd
 The first uses a string expansion, the result of which must be a domain list.
 domains = lsearch;/some/file
 .endd
 The first uses a string expansion, the result of which must be a domain list.

+.new
+The key for an expansion-style lookup must be given explicitly.
+.wen

 No strings have been specified for a successful or a failing lookup; the
 defaults in this case are the looked-up data and an empty string, respectively.
 The expansion takes place before the string is processed as a list, and the
 No strings have been specified for a successful or a failing lookup; the
 defaults in this case are the looked-up data and an empty string, respectively.
 The expansion takes place before the string is processed as a list, and the


@@ -6779,6 +6782,12 @@ domain2:
 Any data that follows the keys is not relevant when checking that the domain
 matches the list item.
 
 Any data that follows the keys is not relevant when checking that the domain
 matches the list item.
 

+.new
+The key for a list-style lookup is implicit, from the lookup context, if
+the lookup is a single-key type (see below).
+For query-style lookup types the key must be given explicitly.
+.wen
+

 It is possible, though no doubt confusing, to use both kinds of lookup at once.
 Consider a file containing lines like this:
 .code
 It is possible, though no doubt confusing, to use both kinds of lookup at once.
 Consider a file containing lines like this:
 .code