In the notation (a/b/c): {d/e/f) for summarizing the characteristics

In the notation (a/b/c): {d/e/f) for summarizing the characteristics of queuing situation, the letters b and c stand respectively for

1. service time distribution & queue discipline
2. number of servers & size of calling source
3. number of servers & queue discipline
4. service time distribution and maximum number allowed in system

b: Service time distribution (usually represented by ‘m’)
d: Queuing discipline (usually represented by ‘GD’)