What do you mean by hotel room account transfer?

As long as the amount is transferred, there is no balance.

Transfer-in and transfer-out are collectively referred to as "carry-over". As for when to call in and when to call out, that is from the perspective of accounting subjects.

For example, month-end profit and loss account carry-forward is "transfer-in" from the perspective of "current year's profit" account and "transfer-out" from the perspective of expense account. The accounting entries that carry forward the expense account amount to this year's profit are collectively referred to as "carry-forward entries".