This site contains information on a few aspects of the Danish register data. Some of it is general and some pertains to specific variables.
Variables:
TIMELON (hourly wage measure):
Short version: Documenting and Improving the Hourly Wage Measure in the Danish IDA Database with Christian Lund, The Danish Journal of Economics, 2016, vol. 1, p. 1-35.
Long version here.
DISCO (occupational code):
Short note on DISCO with Malthe Elholm and Christian Frandsen
ONET and BIBB task data linked to DISCO (large zip file): Here
BRANCHE:
Cross-walk between different nomenclatures of BRANCHE