Editing GPSS (section)

== Data Prefixes ==

Source:<ref>{{Citation |title=General Purpose Simulation System/360: User's Manual |date=1967 |url=https://archive.computerhistory.org/resources/access/text/2021/06/102665359-05-01-acc.pdf |access-date=10 December 2023 }}</ref>

=== Transactions ===
{| class="wikitable"
!Prefix
!Meaning
|-
|Pj
|A parameter of the transaction current being processed by the program.
|-
|M1
|The transit time of the current transaction.
|-
|MPj
|Intermediate transit time of current transaction.
|-
|PR
|Priority of current transaction (0-127).
|}

=== Chains ===
{| class="wikitable"
!Prefix
!Meaning
|-
|CHj
|The current count, which is the number of the transaction on a specified user chain.
|-
|CAj
|The average number of transactions on user chain j.
|-
|CCj
|Total number of entries on user chain j.
|-
|CTj
|Average time per transaction on user chain j.
|}

=== Blocks ===
{| class="wikitable"
!Prefix
!Meaning
|-
|Nj
|The entry count of the total number of transactions which have entered a specified block in the block diagram. This count is automatically maintained by the program. Example: N$SAM for the entry count at block SAM. This count does not include the transaction currently in process at its current block.
|-
|Wj
|The wait count, which is the number of transactions currently waiting at a specified block of the block diagram. This count is also maintained automatically by the program. Example: WSHOLD for the current wait count at block HOLD. This count is also exclusive of the transactions currently in process at its current block.
|}

=== System Attributes ===

==== Quantities ====
{| class="wikitable"
!Prefix
!Meaning
|-
|Kj
|An indication that the integer is a constant. Example K3276 for the integer 3276 or KO for the integer zero.
|-
|RN(x)
|A computed random number (1<=x<=8). The value of the number is an integer between 0 and 999, inclusive, unless the quantity is to be used as the independent variable of a function. In that case, the number is a fraction greater than or equal to zero, but less than one. In either case, all values within the specified range may be considered equally probable.
|-
|C1
|The current value of the simulator clock. This quantity is automatically maintained by the program.
|}

=== Equipment Attributes ===

==== Storages ====
{| class="wikitable"
!Prefix
!Meaning
|-
|Sj
|The contents of a specified storage in the block diagram. The quantity may be modified by ENTER and LEAVE blocks. Example: S2 for the contents of storage (number) 2.
|-
|Rj
|The number of available units of space in the specified storage. This quantity may be modified by ENTER and LEAVE blocks. Example: R195 for the space remaining in storage 195.
|-
|SRj
|Utilization of storage j in parts per thousand, i.e., if the utilization was .65 the computed value would be 650.
|-
|SAj
|Average contents of storage j (truncated).
|-
|SMj
|Maximum contents of storage j. This quantity is automatically maintained by the program.
|-
|SCj
|Number of entries for storage J. This quantity is automatically maintained by the program.
|-
|STj
|Average time each transaction used storage j (truncated).
|}

==== Facilities ====
{| class="wikitable"
!Prefix
!Meaning
|-
|Fj
|The status of the specified facility in the block diagram. This value is zero if the facility is available; otherwise, it is one. This quantity may be modified by SEIZE, RELEASE, PREEMPT, and RETURN blocks. Example: F20 for the status of facility 20.
|-
|FRj
|Utilization of facility j in parts per thousand, i.e., if the utilization was .88 the value of FRj would be 880.
|-
|FCj
|Number of entries for facility j.
|-
|FTj
|Average time each transaction used facility j (truncated).
|}

==== Groups ====
{| class="wikitable"
!Prefix
!Meaning
|-
|Gj
|The current number of members of group j.
|}

=== Statistical Attributes ===

==== Queues ====
{| class="wikitable"
!Prefix
!Meaning
|-
|Qj
|The length of a specified queue in the block diagram. This quantity may be modified by the QUEUE and DEPART blocks. Example: Q50 for the contents of queue 50.
|-
|QAj
|Average contents of queue j (truncated).
|-
|QMj
|'''Maximum''' contents of queue j. This quantity is automatically maintained by the program
|-
|QCj
|Number of entries in queue j. Automatically maintained.
|-
|QZj
|Number of entries in queue j. Automatically maintained.
|-
|QTj
|Average time each transaction was on queue j (including zero entries). When referenced the value will  be truncated to an
integer.
|-
|QXj
|Average time each transaction was on queue j (excluding zero entries). Truncated.
|}

==== Tables ====
{| class="wikitable"
!Prefix
!Meaning
|-
|TBj
|The computed mean value of a specified histogram-type table which is defined by the user. The TABULATE block is used to enter values in one of these tables. Although the computed average can possess a fractional part, it is not retained unless the computed average is to be used as the independent variable of a function. Example: TB42 for '''''the''''' computed mean value of table 42.
|-
|TCj
|Number of entries in table j.
|-
|TDj
|Computed standard deviation of table j.
|}

==== Savevalues ====
{| class="wikitable"
!Prefix
!Meaning
|-
|Xj
|The contents of fullword savevalue j.
|-
|XHj
|The contents of halfword save-value j.
|-
|MXj(a,b)
|The contents of fullword matrix savevalue j, row a, column b. (a and b can be any other SNA)
|-
|MHj(a,b)
|The contents of halfword matrix savevalue j, row a, column b.
|}

==== Computational Attributes ====
{| class="wikitable"
!Prefix
!Meaning
|-
|FNj
|A computed function value. Only the integer portion is retained except when used as a function modifier in GENERATE, ADVANCE or ASSIGN blocks.
|-
|Vj
|An arithmetic combination of Standard Numerical Attributes which is called a variable statement and is defined by the user. Only the integer portion is retained. (See Chapter 4.)
|-
|BVj
|The computed value (1 or 0) of Boolean variable j.
|}

=== Range of the Standard Numerical Attributes ===
{| class="wikitable"
!Entity
!Symbol
!Meaning
|-
|Transactions
|P
|Parameter, fullword[halfword]
|-
|
|PR
|Priority
|-
|
|M1
|Transit time
|-
|
|MP
|Parameter transit time
|-
|Blocks
|N
|Total entry count
|-
|
|W
|Current count
|-
|Facilities
|F
|Boolean 1 or 0 Status of facility
|-
|
|FR
|Utilization (parts/thousarid)
|-
|
|FC
|Entry count
|-
|
|FT
|Average time/transaction'
|-
|Storages
|S
|Current contents of storage
|-
|
|R
|Remaining contents
|-
|
|SR
|Utilization (parts/thousand)
|-
|
|SA
|Average contents•
|-
|
|SM
|Maximum contents
|-
|
|SC
|Entry count
|-
|
|ST
|Average time/transaction•
|-
|Queues
|Q
|Current length of queue
|-
|
|QA
|Average contents•
|-
|
|QM
|Maximum contents
|-
|
|QC
|Total entry count
|-
|
|QZ
|Number of zero entries
|-
|
|QT
|Average time/transaction
|-
|
|QX
|Average time/transaction
excluding zero
|-
|Tables
|TB
|Table mean•
|-
|
|TC
|Entry count
|-
|
|TD
|Standard deviation•
|-
|Savevaules
|X
|Fullword savevaluc
|-
|
|XII
|lialfword savevalue
|-
|Matrix savevalues
|M(a,b)
|Fullword matrix
|-
|
|MH(a, b)
|Halfword matrix
a = row b = column
|-
|Groups
|G
|Number of items in group
|-
|User's chains
|CA
|Average number on chain•
|-
|
|CH
|Current number on chain
|-
|
|CM
|Maximum number on chain
|-
|
|CC
|Total entries
|-
|
|CT
|Average time entry•
|-
|Functions
|FN
|Function
|-
|Variables
|V
|Arithmetic variable
|-
|
|V
|Floating-point variable
|-
|
|BV
|Boolean variable
|-
|Random numbers
|RN1-RN8
|As function argument, returns 0 to 0.99999. Otherwise, 0.999
|-
|Clock
|C1
|Clock time relative to last RESET or CLEAR card.
|}

=== Conditional Operators ===
This is used in '''TEST''' command.
{| class="wikitable"
|E
|Equal
|-
|G
|Greater Than
|-
|GE
|Greater Than or Equal
|-
|L
|Less Than
|-
|LE
|Less Than or Equal
|-
|MAX
|Equal to the Largest such attribute of all Transactions in the Group
|-
|MIN
|Equal to the Smallest such attribute of all Transactions in the Group
|-
|NE
|Unequal to the  reference value specified by Operand E
|}