Neighboring excavation - handover @ ウィキ

As a successor of Hiro, Kei has appointed a person in charge of financial system.
After coming to the office, she has to revise the Tax class due to the revision of the tax law, and she found a method to calculate a value that is not used at all in the class.
She tried to ask Hiro about the method, but he was assigned overseas and she cannot contact with him quickly.
Kei tried to investigate the reason of the method by herself. She looked up the documents of Tax class program comments, design documents, specifications etc, which seemed to be relevant, but there was no reference about the reason for the existence of that method.

How should the successor cope with the unknown problem after the personnel change?

Kei asked about the necessity of the method for Yoshiaki and Joe and others who seemed to be related, but they did not know.
There are other documents for the financial system, such as minutes of the review meeting at the time of development and settlement at the time of procurement, but it seems irrelevant to the method.

Investigate materials that seems to be irrelevant.

Kei decided to investigate the material which seems not to be directly related.
As a result, in the minutes of the review meeting at the time of development, the method was pointed out as a mistake and neede to be deleted.
Kei deleted unnecessary methods at the timing of repair.

It is easier to execute this pattern if an Understandable contents is done. If you can ask your predecessor by Securing an emergensy contact, you do not need to execute this pattern. In addition, if the surrounding material is old, it may be different from actual circumstances. It is important to collect Witnesses for the knowledge and to obtain confirmation.