struct Block
{
    unsigned  day;
    ClassTime start_time;
    size_t    length;
};

This structure represents a block of time during which a class runs.

unsigned day;

The day of the week. 0 = Monday, 4 = Friday.

ClassTime start_time;

The start time of the block.

size_t length;

The length of the block, in 30-minute time units.