### Instruction:

Extract the cause and effect entities from the following sentence:
While the class ManufacturerOfTradeItem is optional, the party identification for the brand owner is required when a manufacturer is present

### Assistant:

KEYWORD: when
VARIABLE: a manufacturer
CONDITION: is present
CAUSE_1: the class ManufacturerOfTradeItem is optional
EFFECT_1: the party identification for the brand owner is required
CAUSE_2: a manufacturer is present

