Deprecated functionality is used
This is a warning message emitted when some deprecated config file commands are used. The actual message that accompanies this error code tells the details. Note that while the statement is deprecated, it continues to work. However, it may no longer work in later versions, so it generally is a good idea to replace it with it’s newer equivalent.
Examples in v7 are the discard action (~ indicator), which has been replaced by the (better) alternative "stop" statement as well as omruleset, which has been replaced by the (much better) "call" statement.