VLS default LUN numbering

[ning_dp]

I'm very confused by the section "default LUN numbering" in the VLS manual.

It says that The VLS automatically assigns a logical unit number (LUN) to each virtual library and tape drive created on the VLS in the order. and the default LUN number will be changed in some conditions.

In fact, we specify LUN number when a LUN is mapped to host, the LUN number is not assigned by VLS automatically.

Does it mean vitual device ID but not LUN number?