There is zero or one current instance.
There is zero to N selected instances.
This is possibly best understood by using a shipped demonstration example.In VLF-ONE
Use Example Applications -> Foundation -> Instance List
The shipped command handlers used are DF_T54H2O (All Entries) and DF_T54H1O (Selected Entries).
Execute Programming Techniques -> Basic -> Selected, Current or All Entries.
The shipped command handlers used are DF_DET22 (All Entries) and DF_DET15 (Selected Entries).