API: HTTP Commands report Success with invalid Folder ID

Question:  

Why does a Create or Update command report Success with the Folder ID is -1 or a string?

Answer:

When you pass a string or negative number to a Folder ID field, the value is ignored.  It will not update the Folder ID, and still allows the rest of the command to complete.  Only zero (Unfiled) and positive values update the folder id.  This is standard practice for non-required parameters.