ABSTRACT
For the following discussion of Ostrom derivation, Ostrom-derivates and flockderivates, we follow the work of Jha and Johnson [639], although most of the proofs are omitted.
A spread in PG(3, q) associated with a flock of a quadratic cone consists of a set of q reguli that mutually share exactly one line. These reguli, called the ‘base’ reguli, may be derived producing ‘new’ spreads.
