RPM basics

When you create an RPM package, you can declare four types of dependencies:
(1) If your package requires a capability provided by another, define a requirement.
(2) If other packages depend on or could eventually depend on a capability in your software, declare the capability your package provides.
(3) If your software (or part of your software) cannot coexist simultaneously with another package, specify a conflict.
(4) If your package deprecates another package or an older version of your own software, define what has become obsolete. If your package changes name, you should list the old name as obsolete.

http://www.ibm.com/developerworks/linux/library/l-rpm3/index.html

http://www.ibm.com/developerworks/linux/library/l-rpm2/index.html

http://www.ibm.com/developerworks/linux/library/l-rpm1/index.html