甲乙

1. Origins, structure, and basic meaning

• Structure: 甲乙 (こうおつ) pairs the ordering labels 甲 and 乙 for parties A and B or for comparing relative merit.
• Basic usage: It distinguishes contract parties and appears in an idiom about two works being equally hard to rank.

2. Common pitfalls and similar expressions

• Contract labels and comparative merit
  • In 甲乙つけがたい, the pair no longer names contract parties; it means that assigning first and second place is difficult.