It is the responsibility of each faculty member to determine the attendance policy for each class, to list it on the course syllabus, and to enforce it. Per university regulation, we are not allowed to make "attendance" a grading category. Instead you may have something like "participation" which can be quantified by posting questions, participating in discussion etc.
You may however, and we very strongly encourage you to, have an "attendance policy" in your syllabus. For example, you may stipulate that students are allowed 1 absence and with each subsequent absence their grade will go down by x points. It can also stipulate how many tardies count as an absence. In other words, "attendance" cannot be a grading category, but instead should be its own policy in your syllabus.
The following is a suggestion for your attendance policy. Modifications are under the purview of each instructor.
e.g. A student may miss a total of one week of class (10% of the quarter) for any reason without a penalty to the participation grade (unless the student is scheduled to present work or hand in an assignment that day). Further absences, regardless of the reason, will affect the participation grade. Arriving late for two classes equates to one absence.
Classes may NOT be held on-campus, off-campus or online on any university holiday. Please plan your syllabus around the university holidays carefully and refer to the Academic Calendar.