if only one statement of responsibility is present on the SOI, then it is core
if more than one statement of responsibility is present on the SOI, then only the one that you choose to record first is core:
if you choose to record all statements, then enter them in the order specified (see Data entry order, below)
if you do not choose to record all statements, then only the first statement in the order specified below is core, but be sure to include any statements that identify creators (see 2.4.2.3 2nd paragraph)