Card Information Structure (CIS) is information about the internal data structure of PC cards.
The CIS information is stored as firmware on the CP cards and is read out as soon as a PCMCIA card or PC card is inserted into a personal computer. It contains the way of formatting and organizing the data on the PC-Card, furthermore the card type, which can be a memory expansion, network or modem card or an interface card, and the information about the bus width, the manufacturer, model numbers etc. The CIS information is stored in so called TIS files. The CIS information is organized in so-called tuples, which are finite lists.