is prefixed with an asterisk (`*`) and the ref points
at a tag object, the value for the field in the object
tag refers is used. When unspecified, defaults to
- `%(refname)`.
+ `%(objectname) SPC %(objecttype) TAB %(refname)`.
+ It also interpolates `%%` to `%`, and `%xx` where `xx`
+ are hex digits interpolates to character with hex code
+ `xx`; for example `%00` interpolates to `\0` (NUL),
+ `%09` to `\t` (TAB) and `%0a` to `\n` (LF).
<pattern>::
If given, the name of the ref is matched against this