Rockwell Automation 9323-S5500D A.I. SERIES MICROLOGIX 1000 AND PLC-500 SOFTW - Manual (Page 195)

Using the Database Editor
9-5
Rung and Page Descriptions
Rung descriptions and page titles assigned to rung numbers generate a pseudo-address
in the format RUNG nnn : xxxx where nnn is the ladder file number and xxxx is the rung
number. These records are always formatted with leading zeros.