Inspect link grpc params

[VolvoEngineering]

Steam inspect link for CS contains 3 params: S for owner steam id, A for asset id and some unclear param D.

I noticed when you request inventory or GetAssetClassInfo this param can change for same instanceid + classid combination every request, even when item is the same.

So i have this questions:

1. Any ideas what does D means and how it is used? It is just some hash to prevent data scraping?
2. Can we rely on any value of D received from steam for persist cache of metadata or it can change and we need to update it in cache every time?

In node-steam-tradeoffer-manager there is cache mechanism that stores descriptions without TTL, so seems like inspect link for any instanceid + classid combination is actual forever, but this D param confusing me 

[Dr. McKay]

12 hours ago, VolvoEngineering said:

I noticed when you request inventory or GetAssetClassInfo this param can change for same instanceid + classid combination every request, even when item is the same.

Are you sure? This shouldn't be possible. Steam caches classid+instanceid pairs indefinitely. The description data should never change.

12 hours ago, VolvoEngineering said:

Any ideas what does D means and how it is used? It is just some hash to prevent data scraping?

Not really, my best guess is that D just stands for "data". It very likely is a hash to prevent scraping.

12 hours ago, VolvoEngineering said:

Can we rely on any value of D received from steam for persist cache of metadata or it can change and we need to update it in cache every time?

It's been my experience that any [SM], A, D triplet will work forever to fetch item data.

[VolvoEngineering]

8 hours ago, Dr. McKay said:

Are you sure? This shouldn't be possible. Steam caches classid+instanceid pairs indefinitely. The description data should never change.

Yes, for example classid 4428757074 + instanceid 188530139 + appid 730 gives either 

steam://rungame/730/76561202255233023/+csgo_econ_action_preview%20S%owner_steamid%A%assetid%D17052921834481691997

or

steam://rungame/730/76561202255233023/+csgo_econ_action_preview%20S%owner_steamid%A%assetid%D5055539348984972055

both are valid and links to same item in cs game coordinator