A PCAD cell **C** is a list of 4 objects,
**(c,P,I,T)**, defined as follows:

**c**is a QEPCAD cell structure. The cell represented by**c**is contained in the cell represented by**C**, and**c**is a section if and only if**C**is a section.**P**is NULL if**C**is the root cell, and the parent PCAD cell of**C**otherwise.**I**is defined as follows:**I**= 0 if**C**is the root, and otherwise**C**is the**I**th cell in the stack over**P**, i.e. the stack index of**C**.**T**if**C**is a leaf cell, then**T**is**C**'s truth value. Otherwise,**T**is a list of**C**'s children.

This structure is "defined" in the file `pcad.h`

(`coarsecad.h`

in my private copy), which defines the
constants: `SC_REP`

,
`SC_PAR`

, `SC_INX`

, and
`SC_CDTV`

, used with `LELTI`

to access **c**, **P**,
**I**, and **T** respectively.

Christopher W. Brown Last modified: Fri Jan 22 16:19:25 EST 1999