\begin{align*} a_k &= \text{Number of arrivals in \(k\)th period} \\ A(t) &= \text{Number of arrivals in \([0,t]\)} \\ A_k &= \text{Arrival time of \(k\)th job} \\ \As_{k} &= \text{Start of service of \(k\)th job} \\ B &= \text{General batch size} \\ B_k &= \text{Batch size at \(k\)th arrival time} \\ c_k &= \text{Service/production capacity in \(k\)th period} \\ c &= \text{Number of servers} \\ C &= \text{General batch size during a service time} \\ C_a^2 &= \text{Squared coefficient of variation of inter-arrival times} \\ C_s^2 &= \text{Squared coefficient of variation of service times} \\ D(t) &= \text{Number of departures in \([0,t]\)} \\ D_k &= \text{Departure time of \(k\)th job} \\ d_k &= \text{Number of departures in \(k\)th period} \\ \delta &= \text{Departure rate} \\ F &= \text{Distribution of service time of a job} \\ I &= \text{Idle time of single server} \\ \J_k &= \text{Sojourn time of \(k\)th job} \\ \L(t) &= \text{Number of customers/jobs in system at time \(t\)} \\ \L_k &= \text{Number in system at end of \(k\)th period} \\ \Ls(t) &= \text{Number of customers/jobs in service at time \(t\)} \\ \lambda &= \text{Arrival rate} \\ \mu &= \text{Service rate} \\ N(t) &= \text{Number of events of a Poisson process in \([0,t]\)} \\ N(s,t) &= \text{Number of arrivals in \((s,t]\)} \\ p(n) &= \text{Long-run time-average that the system contains \(n\) jobs} \\ \pi(n) &= \text{Stationary probability that an arrival sees \(n\) jobs in system} \\ \QQ(t) &= \text{Number of customers/jobs in queue at time \(t\)} \\ \QQ_k &= \text{Queue length as seen by \(k\)th job, or at end of \(k\)th period} \\ \rho &= \text{Utilization of a single server} \\ S &= \text{Generic service time} \\ S_k &= \text{Service time of \(k\)th job} \\ \U &= \text{Busy time of single server} \\ \W &= \text{Generic waiting time (in queue)} \\ \W_{k} &= \text{Waiting time in queue of \(k\)th job} \\ X &= \text{Generic inter-arrival time between two consecutive jobs} \\ X_k &= \text{Inter-arrival time between job \(k-1\) and job \(k\)} \\ \end{align*}