The type of the device cover or interlock
specified in this conceptual row in the 'xcmHrDevCoverTable'.
* 'true' - this is a device cover conceptual row;
* 'false' - this is a device interlock conceptual row.
Usage: The the Printer MIB combines the identity of
cover versus interlock with the status of open versus closed, in
one object - 'xcmHrDevCover[TypeCover|StatusOpen]' add clarity.