Field help (IBACFLG) 

When activated, this checkbox specifies that entry a registration bar code is authorized on the physical element(s) linked with the financial asset.
When an asset cannot be registered, only the physical elements that do not have a bar code will be linked with the fixed asset.

In fixed asset creation: 

After validating an asset linked with at least one physical element containing a bar code, this field can no longer be modified.