Internal lock and external lock for point machines

[Peter]

Hello

I read in a document that "Point Machines provided on Main Running lines shall be of external Locked type
and Non-Trailable."
Does it imply that all Point Machines come with Internal Locking and that for Main Line use, additional External Locking must also be provided?

Thanks

Which railway authority does the document relate to? This would not be the case for UK mainline - a point machine with an internal FPL is common.