INITRANS and MAXTRANS are used when you expect multiple access to the same data block.

Every transaction which modifies a block must acquire an entry in the Interested Transaction List (ITL). Space for this list is defined by INITRANS. The ITL grows dynamically as needed by transactions up to the value MAXTRANS. It also shrinks back down to the setting for INITRANS.

INITRANS
The default value is 1 for tables and 2 for clusters and indexes.

MAXTRANS
The default value is an operating system-specific function of block size, not exceeding 255.

HTH.