INFO: attribute calendar is being used in a non-standard way

[ejhyer]

Hi, my files have a dimensions and coordinate time using CF units (epoch) and then a non-coordinate variable atime with dimension time representing analysis time. Checker recommended I put in
time:calendar='standard'
but when I also put in
atime:calendar='standard'
I get this INFO. It seems less correct to leave out the calendar attribute, since it is technically necessary to interpret the units. Is there a deeper explanation why the checker returns this INFO?

[RosalynHatcher]

The standard use for the calendar attribute is on coordinate variables as per http://cfconventions.org/Data/cf-conventions/cf-conventions-1.9/cf-conventions.html#attribute-appendix. When any attribute is used in a non-standard way an informational message is displayed.