All methods in ParPre are based on decomposition of the physical domain into subdomains, with an assignment of one subdomain per processor (or rather: process). Most methods involve a local solve on the subdomain, for which any of the non-parallel Petsc preconditioners can be used.
For the methods that do not have all subdomains operate in parallel (e.g., multiplicative Schwarz as opposed to additive Schwarz), the user can specify the strategy that determines the sequential ordering of the domains. The choices are: natural, red-black, and multicolour.