Before the scan the user has to define the require user data. It can be done in Spock by, e.g.
p09/door/haspp09.01 : nxsetudata sample_name WaterIt provides data for CLIENT datasources, i.e. sample_name=Water.
The user data can be unset by e.g. :
p09/door/haspp09.01 : nxsusetudata SampleName
In the similar way a user can add her/his free-form comments, e.g.:
p09/door/haspp09.01 : nxsetudata user_comment "mono was very stable"The value of user_comment will be store in default location of NeXus file.