This guide is for marking students who don't come in on a set timetable and instead come in as required or scheduled by teachers.
First a group must have the 'Needs Block Dates' switch off. By default all groups have this on as this is the normal way the roll call works. Admins can turn this switch on or off from the Group Administration screen.
Next, teacher's who are going to be adding the attendance must have the 'Bypass block dates' permission added to thier account. This two step process is to make sure that teachers don't accidentally add out of block attendances to students that shouldn't have them.
Lastly, the teacher who has the required permission can go to the student's profile, click on the 'Roll call' button and then add a new attendance by clicking the green 'Add Attendance' button. Instead of getting an error about group dates not being set up, the attendance row will instead be added for the student.