UNLOCK ALL Within An MFS
The UNLOCK.ALL call functions differently than other lock calls. When an BASIC+ UNLOCK ALL statement is executed, the system does not pass individual lock calls to each open file. Instead, the system reviews the list of installed filing systems and makes a single UNLOCK.ALL call to each filing system.
Because this call is directed to the filing system specifically, an MFS receiving an UNLOCK.ALL call does not need to pass the call along to subsequent filing systems. If a call is attempted to the next MFS, a load error will occur.
The system will call all MFSs that have been installed during the current session, even if no files using that MFS are currently attached.
The MFS should simply perform any tasks required to clear all pending locks for that filing system. When this task is complete, the MFS should return with status set to true.
