System Life Cycle - The security practitioner should be familiar with the Systems Life Cycle (SLC)/Systems Development Life Cycle (SDLC). The steps are complementary, and in most instances, SLC and SDLC are used interchangeably (see the definition in the glossary of the Information Security Management Handbook, 6th edition) . Generally, the SLC includes operations, maintenance and disposal, while SDLC ends with the transition to production.