Can I modify "System Equity" indicator?

[Barry Kaufman <102577.325@xxxxxxxxxxxxxx>]

I would like to plot System Equity as a percentage change rather than a
dollar amount.  The System Equity indicator references I_OpenEquity and
I_ClosedEquity, but I don't find these as functions or other indicators and
I don't find help reference to them as EL words.  How can I get to these to
apply an EL formula which can modify them on each bar?

Thanks, Barry.