PATCHes and lost updates
When a business process spans multiple calls, the first call is typically either a GET that retrieves data, or a POST that creates data. If the business process involves a PATCH, this PATCH typically comes after the first call, and it typically acts on a resource that was queried for or created in a previous call.
It is possible for some other process to modify the data after the initial GET/POST, but before the subsequent PATCH. This can cause a lost update. Within the system APIs, a lost update is a modification made to a resource that unintentionally overwrites changes made by some other process.
You can prevent lost updates using checksums. For more information, see Lost updates and checksums.