On what distribution?
Normally, the runlevel scripts are identified by <k>nn<name>, where <k> is either S (meaning start on entry to run level), or K - (stop on runlevel exit). The "nn" is a two digit number specifying the order. The scripts are run based on an alphabetical order, hence the "nn" determines the order of the scripts; if two scripts have the same number, then it is determined by the <name> order.
Some distributions don't use run levels anymore (Fedora, SUSE, and derivatives. There may be others).