I sent an email to Roy at Team-C asking what the various markings on the springs are. This is what he said...
"The more lazer etching marks, the softer the spring.
The stock Big Bore springs are considered Mediums, but they are not marked. When you buy stock replacements, such as the TU0250F/R, you will then see double etch marks on both ends, indicating "Medium" rate. The options available are the single etch marked Hards, and the triple-etch marked Softs.
The current set of Big Bore springs were all originally designed for the front and rear of the TC02 buggy and TC02T stadium truck. Therefore, when setting up an SCT, it has been best to use long (rears) in the front, with or without the little helper springs, depending on chassis weight/bias."
So there you have it.
-Dean