How to see updates of an asset?

Hello, I am still figuring out SPTs and I need a little help understanding this.

Exploring the transactions data: when an asset is first created using SPTassetActivate the token details (symbol, max supply, … etc) are displayed in the raw transaction in the “systx” object, while when there is a SPTAssetUpdate Transaction, the raw transaction has no specification for what was updated, I can usually see ( “update_flags”: 0 ) only and I don’t know what it actually means.

Anyway, my question is how to know the updates that happened to an asset in a specefic transaction?