Number lines in a verbatim environment
The extension function expects the following variables to be
available in the calling context: $linenumbering.everyNth,
$linenumbering.width, $linenumbering.separator, and
$stylesheet.result.type.
Saxon extension to decorate a result tree fragment with line numbers.
Constructor for the NumberLinesEmitter.
The number of columns seen.
The number of columns seen.
The number of lines seen.