INSTRUCTION	DESCRIPTION
ADVANCE	Holds a transaction for a specified time interval Operand1 - Average Time ; Operand2 - Deviation ( 1/2 Interval )
DEPART	Leave a specified queue Operand1 - Queue Address
ENTER	Enter a storage Operand1 - Storage Address
GENERATE	Generates a transaction Operand1 - Average Time Between 2 Transaction ; Operand2 - Deviation ( 1/2 Interval ) Operand3 - Time to Generate 1 Transaction ; Operand4 - Total Number of Transactions Operand5 - Priority
LEAVE	Leave a storage Operand1 - Storage Address
LINK	Admission to a user_queue Operand1 - User_queue Address ; Operand2 - Type of Entry FIFO/LIFO
MARK	Set the ‘Marker’ to the current value
PRIORITY	Transaction priority
QUEUE	Admission to a queue Operand1 - Queue Address
RELEASE	Release a device Operand1 - Device Address
SPLIT	Split a transaction Operand1 - Number of Transactions
GATHER	Merge several transactions Operand1 - Number of Transactions
SEIZE	Seize a device Operand1 - Device Address
TABULATE	Save value for histogram Operand1 - Table Address ; Operand2 - Table Attribute
TERMINATE	Transaction leaves the model Operand1 - Decrement Value
UNLINK	Transaction leaves a user_queue Operand1 - User_Queue Address ; Operand2 - Address in the Queue Operand3 - Number of Transactions Leaving ; Operand4 - Destination Address
RESIT	Reset the simulator
CLEAR	Delete the statistics and reset the clock
START	Start the simulator Operand1 - Terminal Time
OPEN	Open a data base Operand1 - Add or Remove Data 1 - INPUT 2 - OUTPUT Operand2 - Data Base Address
CLOSE	Close data base Operand1 - Data Base Address
INPUT	Read from a data base Operand1 - Data Base Address ; Operand2 - List of Actual Arguments
INPUTLN	Read a Line from a data base Operand1 - Data Base Address ; Operand2 - List of Actual Arguments
PRINT	Write to a data base Operand1 - Data Base Address ; Operand2 - List of Actual Arguments
PRINTLN	Write a line to a data base Operand1 - Data Base Address ; Operand2 - List of Actual Arguments
PLOT	Plots a table of data ( Histogram )
IF - THEN - ELSE	Conditional branching
CASE	Computed conditional branching

Table 1 - Semantics of the most important ISDS instructions