A rod's line weight is typically listed on the blank either in kilograms (e.g. 3-5kg), pounds (e.g. 10-20lb) or as a PE rating (e.g. PE 2-4). This is useful for matching a rod to its intended purpose; however, for lure casting it’s often more useful to match a rod’s ‘lure weight’ rating or ‘casting weight’ rating to the intended lure.
Lure weight and/or casting weight ratings are the same thing by two different names. These ratings are listed on the rod blank in grams (e.g. 4-10g), or ounces (e.g. 1-2oz). This rating is more important these days – with the increasing popularity of braided lines – as anglers often use lines much stronger than necessary to take advantage of braid's thin diameters. It's quite common to use line that breaks well beyond a rods 'line weight' rating (e.g. using 15kg braid on a snapper rod with a line weight rating of 5-7kg). This is why a 'drag rating' can also be found on some rods.
For certain types of medium and heavy tackle fishing a 'drag rating' may also be listed on a rod. The drag rating is an important consideration when line weight and casting weight become irrelevant (e.g. using seemingly unbreakable braid for GTs in shallow water). Heavy jigging and popping rods (like the OCEA Plugger/Jigger, Grappler range) along with some conventional game rods will list a maximum drag rating in kilograms or pounds not to be exceeded when the rod is at 45 degrees (e.g. Max Drag: 16kg).