PMD

PMD files are used to define models accross multiple PSR software. It stores metadata about every attribute and relation.

Good practices

In order to make the PMD file more readable and easier to maintain, we recommend the following good practices:

• Decide whether you want to use PascalCase, snake_case or camelCase and stick to it.
• Always write the name for the Attributes and Collections in English.
• Do not use special characters other than "_" (underscore) in the names.
• Define understandable names for the Attributes and Collections, as other users may use your model in the future.

Defining a model

To define a model Custom_Model_v1, you need to use the following structure:

DEFINE_MODEL MODL:Custom_Model_v1

	...

END_MODEL

Defining a parameter

A parameter can be either a VECTOR or a PARM.

PARM

DEFINE_MODEL MODL:Custom_Model_v1

	...

	PARM INTEGER Iterations
	PARM REAL Price
	PARM STRING Name
	PARM DATE DateOfEvent

	...

END_MODEL

VECTOR

A VECTOR parameter can store the same types as a PARM. Additionally can have an indexing parameter attribute.

Let's say that you have a vector Cost where each index corresponds to a cost in a specific date. We can use an auxiliary indexing vector CostDates to access the cost value correspondent to a given date (see the Graf Files and Time Series example).

DEFINE_MODEL MODL:Custom_Model_v1

	...

	VECTOR DATE CostDates
	VECTOR REAL Cost INDEX CostDates

	...

END_MODEL

Parameters with dimension

A VECTOR or PARM parameter can change according to a given Stage, Scenario and/or Block dimension (see the Graf Files and Time Series example). We can specify whether a parameter is dimensioned using the following syntax:

DEFINE_MODEL MODL:Custom_Model_v1

	...

	PARM INTEGER Iterations DIM(block)

	VECTOR REAL Duration DIM(block) 

	VECTOR DATE CostDates
	VECTOR REAL Cost DIM(block,segment) INDEX CostDates 

	...

END_MODEL

REFERENCE

Besides REAL, INTEGER, STRING and DATE, there is a fith attribute type labeled REFERENCE. It can be stored either in a VECTOR or a PARM.

A REFERENCE represents a relation between two models(or collections, when considering a PSRI study).

It has the following structure:

DEFINE_MODEL MODL:Custom_Model_v1

	...

	PARM REFERENCE Plant TargetCollection  

	VECTOR REFERENCE Items SecondTargetCollection

	...

END_MODEL

In this example, our CustomModelv1 model has two relations:

• a relation of 1 to 1 (for being a PARM parameter) with elements of collection TargetCollection
• a relation of 1 to N (for being a VECTOR parameter) with elements of collection SecondTargetCollection

The Plant and Items parameters store the reference_id of the corresponding elements from collections TargetCollection and SecondTargetCollection, respectively.

Note that the names TargetCollection and SecondTargetCollection are the name of the collections inside the study, not their name in the PMD file. This difference between names is explained in the Model Template manual.

Also, we define a REFERENCE only in the models which play the role of source.

There is another way to define relations in a study. For that, see the Relation Mapper manual.