noun
original source of re-established family register; old family register
A legal term referring to the original family register that served as the basis when a new family register was created due to legal reforms or re-establishment. It is a historical record kept alongside the current register.
改製原戸籍は、現在の戸籍とともに保管されている。
The original source of the re-established family register is kept together with the current family register.
相続手続きのために、改製原戸籍の謄本が必要になることがある。
For inheritance procedures, a certified copy of the old family register may be required.
Compound of 改製 (re-establishment, reform) + 原 (original) + 戸籍 (family register). The term is a legal coinage reflecting the process of creating a new family register based on an older one.