TCG TSS System Level API and TPM Command Transmission Interface Specification
The scope of this document is to describe all the software interfaces to the TSS System API (SAPI) and TPM Command Transmission Interface (TCTI). Both of these interfaces are part of the TPM Software Stack (TSS).
The TSS is a software stack designed to isolate TPM application programmers from the low level details of interfacing to the TPM. The TSS consists of multiple layers: Feature API, Enhanced System API, System API, TCTI, TAB, resource manager, and TPM driver.