MARC 509 ESTC staff note
MARC field 509 is defined locally by the English Short-Title Catalogue to contain informal staff notes. They appear in Hamnet with the label "ESTC staff note," and in the ESTC as " Uncontrolled note."
Policy and formulation
509 notes came into Hamnet as part of the ESTC load in January 2004.
Since these notes were never meant for public consumption, they are often cryptic, sometimes incomprehensible. Nevertheless, some notes signal additional information and important discrepancies between recorded bibliographic description and evidence from individual copies. As of January 2017, they are included in the default Hamnet view.
In general, leave them in the Hamnet record unless they are misleading or otherwise cause confusion.