In general, when you can efficiently write the desired operation in EPL, an all-EPL solution is preferable to one that involves custom-developed plug-ins. Apama customers who experience problems with correlator stability when using custom-developed plug-ins will be asked by Software AG Global Support to remove the plug-in and reproduce the problem prior to being offered further technical help. Software AG Global Support lifts this restriction only if the plug-ins have certification from Apama product management.