Do a search for Contacts.h in your Palm SDK header files. There will be more than one version (at least in the 5.1 version of the SDK I see more than one). The version that you want is in the 2.0\pub subfolder.
That header file contains the function prototypes that I use to grab stuff from the contacts database. -- For information on using the PalmSource Developer Forums, or to unsubscribe, please see http://www.palmos.com/dev/support/forums/
