The information in this Wiki Page applies to TANE, TRS19, Trainz Plus and TRS22.

What Are Parent and Child Rules?

	Rules that act as Parent Rules can have one or more sub-rules or Child Rules under them
	Rules are edited and managed by the Session Editor in Surveyor

More information on the Session Editor can be found on the Trainz Wiki Page at:-

Using the Session Editor

Most Parent Rules are used as "decision makers" in Trainz Sessions. They decide if or when other rules, the Child Rules, will be executed. Some Parent Rules control how those Child Rules are executed.

Notes:

	Only certain rules can be Parent Rules. See the Trainz Wiki page List of Parent Rules for details
	Most Parent Rules will either wait for a specific event or perform a test or a comparison. They will execute their Child Rules when the event occurs or the test/comparison is true
	Any rule can be a Child Rule including other Parent Rules

Session rules can be arranged in a hierarchical fashion, in a series of levels as shown in the example on the left. A Parent Rule can be used to group together a set of rules at a lower level in the hierarchy. The rules that are grouped together under a Parent Rule are the Child Rules.

Child Rules can also be Parent Rules that group together other rules at an even lower level. This creates multiple levels in the hierarchy.

The Parent Rule at the head of each level in the hierarchy acts as a switch that directs the Trainz session to either ignore (skip over) or obey (execute) the Child Rules under its control.

Rules that act as Child Rules are indented under a Parent Rule

Steps: To indent a rule:-
	select (Left Click) the rule to be indented
	Left Click the Right Arrow Indent tool at the bottom of the Session Editor

Parent/Child Rule Example

In the following example, a Trigger Check Rule is acting as the switch that decides whether or not its child rules will be executed. If the Trigger is activated, for example by a particular train passing over its track trigger, then its child rules will be executed. Otherwise the Trigger Check Rule will wait indefinitely until that event occurs, or the session is terminated.

	the cause of the trigger event is set in the properties of the Trigger Check Rule
	the message shown is set in the properties of the Message Popup Rule
	the duration of the wait is set in the properties of the Wait Rule

In the screenshot above, the

Line 1 : Trigger Check Rule is a Parent Rule. It has rules indented below it which are its Child Rules:-

Line 2 : Simultaneous List Rule is indented under the Trigger Check Rule so it is a Child of that rule. It is also a Parent Rule and it has its own Child Rules indented below it:-

Line 3 : Message Popup Rule is indented under the Simultaneous List Rule so it is a Child of that rule

Line 4 : Wait Rule is indented under the Simultaneous List Rule so it is a Child of that rule. It is also a Parent Rule as it has rules indented below it

Line 5 : Close Message Popup Rule is indented under the Wait Rule so it is a Child of that rule

Sequence of Events

When the consist identified in the Trigger Check Rule, a Parent Rule, reaches the set trigger, the Trigger Event is activated and its Child Rules are executed

The Simultaneous List Rule, a Parent Rule, is then executed. It executes all its Child Rules immediately and simultaneously

Simultaneously...
	The Message Popup Rule is executed
	The Wait Rule is executed. This is set to force a 20 second wait, then ...

The Close Message Popup Rule is executed. This closes the Message window created by the Message Popup Rule

Since the Close Message Popup Rule is the last child rule under the Wait Rule, when it has completed its task (closing the message popup) it will terminate the Wait Parent Rule

Since it is also the last child rule under the Simultaneous List Rule it will terminate that Parent Rule

Finally, since it is the last child rule under the Trigger Check Rule, it also terminates that Parent Rule

Ordered Lists vs Simultaneous Lists

The majority of sibling Child Rules, rules that are at the same indent level under a Parent Rule, will be executed in order (an Ordered List) or simultaneously (a Simultaneous List).

Ordered Lists

	Details for this rule can be found at Ordered List Rule
	Ordered Lists are shown with numbered icons on each Child Rule which indicates the order in which they will be executed

	Notes:
	an Ordered List can be set to repeat a set number of times
	each Child Rule in the sequence must be completed before the next Child Rule can be executed
	an Ordered List is completed when the last Child Rule is completed

Because some rules will wait for an event (such as a mouse click, a set time or a time period, a trigger, etc) before they are completed, it is possible for the Ordered List to hang indefinitely waiting for the event to occur. This will stop that particular Child Rule from being completed and any following Child Rules from being started. So, if possible, place Child Rules that are event dependent at the end of an ordered list.

Setting the Options

The rule settings allow you to control how many times an Ordered List will run.

Steps: To set the repeat options for an Ordered List:-

select (Left Click on) the Ordered List in the Session Editor

select (Left Click on) the Edit button at the bottom of the Session Editor to open the Ordered List properties window

Select an Option Button:-

	This process will repeat 1 time(s)
	This process will repeat forever

to change the number of repeats to any required number Left Click on the 1 and enter a new value. Click the

to accept the change

to accept the new rule settings Left Click on the

or the Save Changes button (depending on your version of Trainz) in the rule properties window

	Notes:
	the minimum number is 1 which means that the Ordered List will execute once only
	the "repeat forever" option will force the list to restart again endlessly

Simultaneous Lists

	Details for this rule can be found at Simultaneous List Rule
	Simultaneous Lists are shown with equality (=) icons on each Child Rule which indicates that they will all be executed at the same time

	Notes:
	a Simultaneous List can be set to complete when all the Child Rules have been completed, or when any one of the Child Rules has been completed
	while all Child Rules in a Simultaneous List will start at the same time, some will take longer to complete than others and some may wait for a particular event before they can complete

Setting the Options

The rule settings allow you to control how a Simultaneous List will be terminated.

Steps: To set the "completion" options for a Simultaneous List:-

select (Left Click on) the Simultaneous List in the Session Editor

select (Left Click on) the Edit button at the bottom of the Session Editor to open the Simultaneous List properties window

Depending on your version of Trainz 2 or 3 options are presented by cycling ("clicking") through the underlined text.

Select an option:-

	all child rules have reached a completed state
	all child rules have reached a 'was completed' state
	one of the child rules has completed

to accept the new rule settings Left Click on the

or the Save Changes button (depending on your version of Trainz) in the rule properties window

	Notes:
	the first option, "all child rules have reached a completed state", means that the Simultaneous List will wait until ALL child rules have been completed before terminating. Some child rules may wait for an event, such as a trigger or a set time, before they terminate
	the second option, "all child rules have reached a 'was completed' state", is needed for the UDS feature in TRS19 Platinium and later versions that allows you to switch between Driver and Surveyor. If you make the switch back to Driver when some rules have been completed but others have not, then the completed child rules will not be restarted and the Simultaneous Rule will wait until all the child rules reach the was completed state before it terminates
	the third option, "one of the child rules has completed" will terminate the Simultaneous Rule, and any child rules that have not yet completed, as soon as one child rule completes

Other Types of Lists

Progressive Lists

	Details for this rule can be found at Progressive List Rule
	Progressive Lists are shown with numbered icons on each Child Rule which indicates the progressive order in which they will be executed on each cycle of the list

	Notes:
	a Progressive List executes only a single child rule each time it runs
	on the first run of a Progressive List, only the first Child Rule is executed. On the second run, the second Child Rule is executed. On the third run the third Child Rule is executed, etc. Until all the child rules have been executed

Setting the Options

The rule settings allow you to control what happens after the last child rule in a Progressive List has been completed.

Steps: To set the "completion" options for a Progressive List:-

select (Left Click on) the Progressive List in the Session Editor

select (Left Click on) the Edit button at the bottom of the Session Editor to open the Progressive List properties window

You can select from 3 options by cycling ("clicking") through the underlined text.

Select an option:-

	... successive runs will do nothing - after the last child rule has been completed the Progressive Rule will terminate
	... last child .... will be used for all successive runs - after the last child rule has been completed the Progressive Rule will repeat that child rule on all further runs
	... the first child is chosen again - after the last child rule has been completed the Progressive Rule will start with the first child rule again and it will repeat the sequence

to accept the new rule settings Left Click on the

or the Save Changes button (depending on your version of Trainz) in the rule properties window

Random Lists

	Details for this rule can be found at Random List Rule
	Random Lists are shown with "dot" icons on each Child Rule which indicates that ONE of them will be selected at random

	Notes:
	a Random List will run ONCE ONLY
	a child rule will be selected at random and once that child rule has been completed, the Random List will terminate
	there are no control options for a Random List

Reset Lists

	Details for this rule can be found at Reset List Rule
	Reset Lists are shown with equality (=) icons on each Child Rule which indicates that they will all be executed at the same time

	Notes:
	a Reset List will never terminate. It will run continuously
	after the last child rule has been completed, all the child rules will be reset and executed again
	there are no control options for a Reset List

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This page was created by Trainz user pware in May 2018 and was last updated as shown below.

How to Use Parent and Child Rules

Contents

What Are Parent and Child Rules?

Parent/Child Rule Example

Ordered Lists vs Simultaneous Lists

Ordered Lists

Simultaneous Lists

Other Types of Lists

Progressive Lists

Random Lists

Reset Lists

Trainz Wiki

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