How to build an asset inventory for 27001

How do you know WHAT assets are  to be included in the ISO-27K Asset Inventory?

This question and variants of the "What are assets [for ISO27K]?" comes up often and has seen much discussion on the various InfoSec forums I subscribe to.

Perhaps some ITIL influence is need.  Or perhaps not since that might be too reductionist.

The important thing to note here is that the POV of the accountants/book-keepers is not the same as the ISO27K one. To them, an asset is something that was purchased and either depreciates in value, according to the rules of the tax authority you operate under, or appreciates in value (perhaps) according to the market, such as land and buildings.

Here in Canada, computer hardware and software depreciates PDQ under this scheme, so that the essential software on which you company depends is deemed worthless by the accountants. Their view is that depreciable assets should be replaced when they reach the end of their accounting-life. Your departmental budget may say different.

Many of the ISO27K Assets are things the accountants don't see: data, processes, relationships, know-how, documentation.