saxon:last-modified
Returns the date and time when a file was modified.
last-modified($uri as xs:string?) ➔ xs:dateTime
| Arguments | |||
| 
 | $uri | xs:string? | The URI of the required file | 
| Result | xs:dateTime | ||
Namespace
http://saxon.sf.net/
Notes on the Saxon implementation
Available since Saxon 9.0. The specification of this function was changed in Saxon 9.2.
          To find the last-modified date of the file from which a given node was loaded, use
            saxon:last-modified(document-uri($node)). 
Details
If the argument is an empty sequence, the result is an empty sequence.
Otherwise the argument must be a valid URI. If it is a relative URI, this will be
            resolved against the base URI from the static context. The function has been tested with
            URIs using the file and http schemes, and is not guaranteed to
            give a result with other URI schemes (or indeed with these, under all
            circumstances).
The function returns an xs:dateTime value which will usually be in a
            specific timezone. The result can therefore be formatted using the
              format-dateTime() function, or input to arithmetic and comparisons
            against other dates and times.
If the URI is not syntactically valid, error FODC0005 is thrown. If the resource identified by the URI cannot be retrieved, error FODC0002 is thrown. If the resource is successfully retrieved but no date/time information is available, the function returns an empty sequence.
Example:
format-dateTime(file-last-modified(resolve-uri('lookup.xml', static-base-uri()))