VC4 Use the VC4 subtab to provision the line parameters on the cards or ports. Item Description VC4 The VC4 number. Enable IPPM Allows you to enable intermediate path performance monitoring (IPPM). SD Ber Level (STM1E-12 cards only) Displays the signal failure bit error rate. SF Ber Level (STM1E-12 cards only) Displays the signal degrade bit error rate. Apply Applies changes made to the fields in the tab. Reset Cancels any changes to the tab and returns the fields to their last-saved settings. Help Displays context-sensitive help.