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How to add parameter information

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Note

Manual authoring of XML-based help is very difficult. The PlatyPS module allows you to write help in Markdown and then convert it to XML-based help. This makes it much easier to write and maintain help. PlatyPS can also create the Updateable Help packages for you. For more information, see Create XML-based help using PlatyPS.

This section describes how to add content that's displayed in the PARAMETERS section of the cmdlet Help topic. The PARAMETERS section of the Help topic lists each of the parameters of the cmdlet and provides a detailed description of each parameter.

The content of the PARAMETERS section should be consistent with the content of the SYNTAX section of the Help topic. It's the responsibility of the Help author to make sure that both the Syntax and Parameters node contain similar XML elements.

Note

For a complete view of a Help file, open one of the dll-Help.xml files located in the PowerShell installation directory. For example, the Microsoft.PowerShell.Commands.Management.dll-Help.xml file contains content for several of the PowerShell cmdlets.

To add parameters

  1. Open the cmdlet Help file and locate the Command node for the cmdlet you are documenting. If you are adding a new cmdlet you will need to create a new Command node. Your Help file will contain a Command node for each cmdlet that you are providing Help content for. Here is an example of a blank Command node.

    <command:command>
</command:command>

  2. Within the Command node, locate the Description node and add a Parameters node as shown below. Only one Parameters node is allowed, and it should immediately follow the Syntax node.

    <command:command>
  <command:details></command:details>
  <maml:description></maml:description>
  <command:syntax></command:syntax>
  <command:parameters>
  </command:parameters>
</command:command>

  3. Within the Parameters node, add a Parameter node for each parameter of the cmdlet as shown below.

    In this example, a Parameter node is added for three parameters.

    <command:parameters>
  <command:parameter></command:parameter>
  <command:parameter></command:parameter>
  <command:parameter></command:parameter>
</command:parameters>

    Because these are the same XML tags that are used in the Syntax node, and because the parameters specified here must match the parameters specified by the Syntax node, you can copy the Parameter nodes from the Syntax node and paste them into the Parameters node. However, be sure to copy only one instance of a Parameter node, even if the parameter is specified in multiple parameter sets in the syntax.

  4. For each Parameter node, set the attribute values that define the characteristics of each parameter. These attributes include the following: required, globbing, pipelineinput, and position.

    <command:parameters>
  <command:parameter required="true" globbing="true"
           pipelineInput="false" position="named">
  </command:parameter>
  <command:parameter required="false" globbing="false"
           pipelineInput="false" position="named">
  </command:parameter>
  <command:parameter required="false" globbing="false"
           pipelineInput="false" position="named" ></command:parameter>
</command:parameters>

  5. For each Parameter node, add the name of the parameter. Here is an example of the parameter name added to the Parameter node.

    <command:parameters>
  <command:parameter required="true" globbing="true"
           pipelineInput="false" position="named">
    <maml:name> Add parameter name...  </maml:name>
  </command:parameter>
</command:parameters>

  6. For each Parameter node, add the description of the parameter. Here is an example of the parameter description added to the Parameter node.

    <command:parameters>
  <command:parameter required="true" globbing="true"
           pipelineInput="false" position="named">
    <maml:name> Add parameter name...  </maml:name>
    <maml:description>
      <maml:para> Add parameter description... </maml:para>
    </maml:description>
  </command:parameter>
</command:parameters>

  7. For each Parameter node, add the .NET type of the parameter. The parameter type is displayed along with the parameter name.

    Here is an example of the parameter .NET type added to the Parameter node.

    <command:parameters>
  <command:parameter required="true" globbing="true"
           pipelineInput="false" position="named">
    <maml:name> Add parameter name...  </maml:name>
    <maml:description>
      <maml:para> Add parameter description... </maml:para>
    </maml:description>
    <dev:type> Add .NET Framework type... </dev:type>
  </command:parameter>
</command:parameters>

  8. For each Parameter node, add the default value of the parameter. The following sentence is added to the parameter description when the content is displayed: DefaultValue is the default.

    Here is an example of the parameter default value is added to the Parameter node.

    <command:parameters>
  <command:parameter required="true" globbing="true"
           pipelineInput="false" position="named">
    <maml:name> Add parameter name...  </maml:name>
    <maml:description>
      <maml:para> Add parameter description... </maml:para>
    </maml:description>
    <dev:type> Add .NET Framework type... </dev:type>
    <dev:defaultvalue> Add default value...</dev:defaultvalue>
  </command:parameter>
</command:parameters>

  9. For each Parameter that has multiple values, add a possibleValues node.

    Here is an example of the of a possibleValues node that defines two possible values for the parameter

    <dev:possibleValues>
  <dev:possibleValue>
    <dev:value>Unknown</dev:value>
    <maml:description>
      <maml:para></maml:para>
    </maml:description>
  </dev:possibleValue>
  <dev:possibleValue>
    <dev:value>String</dev:value>
    <maml:description>
      <maml:para></maml:para>
    </maml:description>
  </dev:possibleValue>
</dev:possibleValues>

Here are some things to remember when adding parameters.

  • The attributes of the parameter aren't displayed in all views of the cmdlet Help topic. However, they're displayed in a table following the parameter description when the user asks for the Full (Get-Help <cmdletname> -Full) or Parameter (Get-Help <cmdletname> -Parameter) view of the topic.

  • The parameter description is one of the most important parts of a cmdlet Help topic. The description should be brief, as well as thorough. Also, remember that if the parameter description becomes too long, such as when two parameters interact with each other, you can add more content in the NOTES section of the cmdlet Help topic.

    The parameter description provides two types of information.

  • What the cmdlet does when the parameter is used.

  • What a legal value is for the parameter.

  • Because the parameter values are expressed as .NET objects, users need more information about these values than they would in a traditional command-line Help. Tell the user what type of data the parameter is designed to accept, and include examples.

The default value of the parameter is the value that's used if the parameter isn't specified on the command line. Note that the default value is optional, and isn't needed for some parameters, such as required parameters. However, you should specify a default value for most optional parameters.

The default value helps the user to understand the effect of not using the parameter. Describe the default value very specifically, such as the "Current directory" or the "PowerShell installation directory ($PSHOME)" for an optional path. You can also write a sentence that describes the default, such as the following sentence used for the PassThru parameter: "If PassThru isn't specified, the cmdlet doesn't pass objects down the pipeline." Also, because the value is displayed opposite the field name Default value, you don't need to include the term "default value" in the entry.

The default value of the parameter isn't displayed in all views of the cmdlet Help topic. However, it's displayed in a table (along with the parameter attributes) following the parameter description when the user asks for the Full (Get-Help <cmdletname> -Full) or Parameter (Get-Help <cmdletname> -Parameter) view of the topic.

The following XML shows a pair of <dev:defaultValue> tags added to the <command:parameter> node. Notice that the default value follows immediately after the closing </command:parameterValue> tag (when the parameter value is specified) or the closing </maml:description> tag of the parameter description. name.

<command:parameters>
  <command:parameter required="true" globbing="true"
           pipelineInput="false" position="named">
    <maml:name> Parameter name </maml:name>
    <maml:description>
      <maml:para> Parameter Description </maml:para>
    </maml:description>
    <command:parameterValue required="true">
      Value
    </command:parameterValue>
    <dev:defaultValue> Default parameter value </dev:defaultValue>
  </command:parameter>
</command:parameters>

Add Values for Enumerated Types

If the parameter has multiple values or values of an enumerated type, you can use an optional <dev:possibleValues> node. This node allows you to specify a name and description for multiple values.

Be aware that the descriptions of the enumerated values don't appear in any of the default Help views displayed by the Get-Help cmdlet, but other Help viewers may display this content in their views.

The following XML shows a <dev:possibleValues> node with two values specified.

<command:parameters>
  <command:parameter required="true" globbing="true"
           pipelineInput="false" position="named">
    <maml:name> Parameter name </maml:name>
    <maml:description>
      <maml:para> Parameter Description </maml:para>
    </maml:description>
    <command:parameterValue required="true">
      Value
    </command:parameterValue>
    <dev:defaultValue> Default parameter value </dev:defaultValue>
    <dev:possibleValues>
      <dev:possibleValue>
        <dev:value> Value 1 </dev:value>
        <maml:description>
          <maml:para> Description 1 </maml:para>
        </maml:description>
      <dev:possibleValue>
      <dev:possibleValue>
        <dev:value> Value 2 </dev:value>
        <maml:description>
          <maml:para> Description 2 </maml:para>
        </maml:description>
      <dev:possibleValue>
    </dev:possibleValues>
  </command:parameter>
</command:parameters>