RSI is a misnomer as the only input is a single security's data, so there is no indexing versus another security; RSI is similar to the (also mis-named) stochastic function. RSC requires two security data inputs and indexes them. wabbit [:D]

MetaStock has 3 similar ways to relate one security with another: 1. Relative Strength Comparitive indicator 2. Relative Performance indicator 3. Composite (File>New>Composite Instrument in 12.0) 1 and 2 are essentially identical except for the starting value. #3 is the most flexible since you can control the operator that relates them. You can search the MetaStock Help for more details on each of these.