74HC86 XOR datasheet say Schmitt trigger "action" - is there anything special about it?
According to TI's "AHC/AHCT Designer's Guide February 2000", Section 2, "DC Characteristics", subsection 1, "Input Circuit", interfaces with lower-speed circuits with a lower slew rate can cause oscillation at 74AHC/T inputs. To prevent this, 74AHC/T input stages contain a feedback loop which causes the input to have hysteresis much as a Schmitt trigger input would without containing all the circuitry for an actual Schmitt trigger input.



However, the guide goes on to say:


  Hysteresis in the input circuit is intended only to process reliably signals that have a slew rate of &lt;10 ns/V. With a signal swing
  of 5 V, this corresponds to rise and fall times of about 50 ns. If signals with considerably longer rise and fall times are processed,
  the specially developed Schmitt triggers, such as the SN74AHC(T)14, should be used. These components have a considerably
  larger hysteresis of about 800 mV at VCC = 5 V and, therefore, allow processing of very slow edges without any problems.