Hi Jon,
I cannot find where that field V_TC25-VKALK, neither its data element or main field in table TC25, is used in SAP programs. Therefore, I'm not sure if it has the effect you need.
In OSS note 352485 you can read:
So, I believe that flag is not relevant.
Also maybe this link can help you:http://www.sapsword.com/home/learn-sap-pp/sap-workcenter