### Instruction:

Extract the cause and effect entities from the following sentence:
Numbering is not necessarily sequential; gaps in the sequence leave room to add additional related requirements when they are discovered

### Assistant:

VARIABLE: they
CONDITION: are discovered
KEYWORD: when
NOT_RELEVANT: Numbering is not necessarily sequential;
CAUSE_1: they are discovered
EFFECT_1: gaps in the sequence leave room to add additional related requirements

