Modules
Here is a list of all modules:

Building & signing packages: |
Build API. | API for building packages
Signature Tags API. | List of signature tags
Signature API. | How to add or remove a signature from a package header
Data types: |
RPM data types. | The abstract RPM data types
String Manipulation API. | String Manipulation API
String Pool API. | How to store strings in pools
(un)Installing packages: |
Dependency Set API. | How to compare dependencies
Callback signature & types. | The signature of function to register as callback and the cases where it can be called
Transaction Set API. | How to create, run & destroy a package transaction
Transaction Element API. | How to retrieve information from a transaction element
Problem Set API. | Problem Set API
Problem Element API. | Problem Element API
Verify API. | How to verify a package
File Info Set API. | File Info Set API
File Info Set Iterator API. | File Info Set Iterator API
File Classification API. | Structures and methods for build-time file classification
RPM keyring API. | RPM keyring API
Macro API. | Macro API
Logging API. | RPM Logging facilities
OpenPGP API. | OpenPGP constants and structures from RFC-2440
Querying package headers: |
Header API. | How to manipulate package headers (which carries all information about a package)
RPM Tag API. | Manipulating RPM tags (accessing values, types, ...)
RPM Tag Data Container API. | How to retrieve data from package headers
I/O |
Header API. | How to manipulate package headers (which carries all information about a package)
Database API. | Opening & accessing the RPM indices using Berkeley DB (the so called rpmdb)
RPM IO API. | The RPM IO API (Fd_t is RPM equivalent to libc's FILE)
File and Path Manipulation API. | File and path manipulation helper functions
URL Manipulation API. | A couple utils for URL Manipulation
Argument Manipulation API. | Argument Manipulation API
Command Line API. | Parsing RPM command line arguments
Signal Queue API. | Signal Queue API
Statistics API. | Statistics API
RPMRC. | Reading config files and getting some important configuration values