第三条の十二（遺族厚生年金に関する事務の特例）
Article 3-12Special Provisions on Affairs Relating to Survivors' Employees' Pension
Where a deceased insured person or person who was an insured person in relation to a survivors' employees' pension (limited to one paid by reason of falling under Article 58, paragraph (1), item (ii) or (iii) of the Act) has no insured period relating to the insured category on the day of initial examination prescribed in item (ii) of that paragraph or on the day of initial examination for the injury or illness relating to the disability that was the ground for payment of the disability employees' pension prescribed in item (iii) of that paragraph, by the month that includes the day of death, the affairs relating to the payment of that survivors' employees' pension are to be performed by the persons specified in each item of Article 2-5, paragraph (1) of the Act, in accordance with the insured category specified in each of the following items for the case listed in that item.
where there has been a change in the insured category in the month that includes the day of initial examination prescribed in Article 58, paragraph (1), item (ii) of the Act or the day of initial examination for the injury or illness relating to the disability that was the ground for payment of the disability employees' pension prescribed in item (iii) of that paragraph (excluding the case listed in the following item): the insured category after the change (where there has been a change in the insured category two or more times, the last insured category);
法第五十八条第一項第二号に規定する初診日又は同項第三号に規定する障害厚生年金の支給事由となつた障害に係る傷病の初診日の属する月において被保険者の種別に変更があつた場合（次号に掲げる場合を除く。） 変更後の被保険者の種別（二回以上被保険者の種別に変更があつた場合は、最後の被保険者の種別）
where the month that includes the day of initial examination prescribed in Article 58, paragraph (1), item (ii) of the Act or the day of initial examination for the injury or illness relating to the disability that was the ground for payment of the disability employees' pension prescribed in item (iii) of that paragraph is an insured period under the National Pension (excluding the period as a category 2 insured person): the insured category relating to the insured period that the deceased insured person or person who was an insured person has.
法第五十八条第一項第二号に規定する初診日又は同項第三号に規定する障害厚生年金の支給事由となつた障害に係る傷病の初診日の属する月が国民年金の被保険者期間（第二号被保険者期間を除く。）である場合 当該死亡した被保険者又は被保険者であつた者が有する被保険者期間に係る被保険者の種別
定義第三条の十の二第一項
法第十五条に規定する被保険者の種別
わかりやすく言うと
厚生年金保険の被保険者が第一号から第四号のどれに当たるかの区別です。第二号は国家公務員共済組合の組合員、第三号は地方公務員共済組合の組合員、第四号は私立学校教職員共済制度の加入者、第一号はそれ以外の被保険者です（厚生年金保険法第十五条）。
略称規定第三条の十の二第一項第二号・この規定及び第三条の十二第一項第二号の中だけ
当該障害に係る初診日の属する月が国民年金の被保険者期間（国民年金法第七条第一項第二号に規定する第二号被保険者としての国民年金の被保険者期間（第三条の十二第二号において「第二号被保険者期間」という。）を除く。）である場合 当該受給権者が有す…
わかりやすく言うと
国民年金の第二号被保険者、つまり厚生年金保険の被保険者としての国民年金の被保険者期間のことです（国民年金法第七条第一項第二号）。