The parsing correctly handles SMTPUTF8 Unicode in the string.
-.vitem &*${mask:*&<&'IP&~address'&>&*/*&<&'bit&~count'&>&*}*&
+.vitem &*${mask:*&<&'IP&~address'&>&*/*&<&'bit&~count'&>&*}*& &&&
+ &*${mask_n:*&<&'IP&~address'&>&*/*&<&'bit&~count'&>&*}*&
.cindex "masked IP address"
.cindex "IP address" "masking"
.cindex "CIDR notation"
.code
${mask:10.111.131.206/28}
.endd
-returns the string &"10.111.131.192/28"&. Since this operation is expected to
-be mostly used for looking up masked addresses in files, the result for an IPv6
+returns the string &"10.111.131.192/28"&.
+
+Since this operation is expected to
+be mostly used for looking up masked addresses in files, the
+.new
+normal
+.wen
+result for an IPv6
address uses dots to separate components instead of colons, because colon
terminates a key string in lsearch files. So, for example,
.code
.code
3ffe.ffff.836f.0a00.000a.0800.2000.0000/99
.endd
+.new
+If the optional form &*mask_n*& is used, IPv6 address result are instead
+returned in normailsed form, using colons and with zero-compression.
+.wen
Letters in IPv6 addresses are always output in lower case.