text/calendar vs application/ics

[Conrad Hughes]

When I mhshow a message with a text/calendar attachment, it's inlined
using mhical; if the attachment type is changed to application/ics, it's
suppressed instead.  I'm using the latest mhn.defaults from the git
repo, which contains

  mhshow-show-text/calendar: mhical -infile %F
  mhshow-show-application/ics: mhical -infile %F

.. any idea where I should be looking for something else that might
differentiate the two?

Conrad