When setting up a meeting request and to view if attendee is available, what does it mean when availability shows black lines (no information option).  Generally, the options are coded if attendee's availability is 'tentative' (light blue), 'busy' (dark blue), 'out of the office' (purple) and 'no information' (with diagonal lines).  When and how would one use 'no information' to display availability

Thank you.