The TLV431 spec as an expample, shows a maximum Ika current rating of +/- 20mA does that mean it can be run "forward biased" as well as reversed in the usual Zener-like direction, and source current as well as sink it?
like if you wanted to press it into service in some situation as an analog to a one-input low voltage op-amp with a large "offset voltage" where its anode voltage might sometimes be higher than its cathode