diff --git a/src/interrupts.s b/src/interrupts.s
index 0c3fe14..d39e044 100644
--- a/src/interrupts.s
+++ b/src/interrupts.s
@@ -182,7 +182,6 @@ cop_jump_table:
 	.word .word0 cop_exec
 	.word .word0 cop_exit
 	.word .word0 cop_volume_initialize
-	.word .word0 cop_volume_format
 	.word .word0 cop_get_environment_value
 	.word .word0 cop_set_environment_value
 	.word .word0 cop_ioctl
@@ -619,10 +618,21 @@ cop_exec:
 cop_exit:
 	cop_rti
 
-cop_volume_initialize:
-	cop_rti
+; -----------------------------------------------------------------------------
+; Function 23: Initialize SD Card
+;
+; If there is an SD card in the slot, then initialize it for use with the system.
+; This means replacing whatever partition table it might have with a super-floppy
+; (SFD) filesystem. The function expects a pointer to a NULL terminated string to
+; use as the volume label.
+;
+; Arguments:
+;		A: Bank of volume label string
+;		Y: Address of volume label string
+; Return Value:
+;		A: Error code
 
-cop_volume_format:
+cop_volume_initialize:
 	cop_rti
 
 cop_get_environment_value: