TOPIC
	about_Command_Syntax

SHORT DESCRIPTION
	Describes the syntax diagrams that are used in Windows PowerShell.


LONG DESCRIPTION
	The Get-Help and Get-Command cmdlets display syntax diagrams to help
	you construct commands correctly. This topic explains how to interpret
	the syntax diagrams.


  Syntax Diagrams
	Each paragraph in a command syntax diagram represents a valid form
	of the command. 

	To construct a command, follow the syntax diagram from left to
	right. Select from among the optional parameters and provide values for
	the placeholders.

	Windows PowerShell uses the following notation for syntax diagrams.

	 <command-name> -<Required Parameter Name> <Required Parameter Value>
					[-<Optional Parameter Name> <Optional Parameter Value>] 
					[-<Optional Switch Parameters>] 
					[-<Optional Parameter Name>] <Required Parameter Value> 


	The following is the syntax for the New-Alias cmdlet.

		New-Alias [-Name] <string> [-Value] <string> [-Description <string>]
			[-Force] [-Option {None | ReadOnly | Constant | Private | AllScope}]
			[-PassThru] [-Scope <string>] [-Confirm] [-WhatIf] [<CommonParameters>]


	The syntax is capitalized for readability, but Windows PowerShell is 
	case-insensitive. 


  The syntax diagram has the following elements.

  Command name
  ------------
	Commands always begin with a command name, such as New-Alias. Type the
	command name or its alias, such a "gcm" for Get-Command. 


  Parameters
  ----------
	The parameters of a command are options that determine what the command
	does. Some parameters take a "value," which is user input to the command.

	For example, the Get-Help command has a Name parameter that lets you
	specify the name of the topic for which help is displayed. The topic
	name is the value of the Name parameter. 

	In a Windows PowerShell command, parameter names always begin with a 
	hyphen. The hyphen tells Windows PowerShell that the item in the command
	is a parameter name.

	For example, to use the Name parameter of New-Alias, you type the following:

		-Name

	Parameters can be mandatory or optional. In a syntax diagram, optional
	items are enclosed in brackets ([ ]).

	For more information about parameters, see about_Parameters.
	

  Parameter Values
  ----------------
	A parameter value is the input that the parameter takes. Because Windows
	PowerShell is based on the Microsoft .NET Framework, parameter values are
	represented in the syntax diagram by their .NET type. 

	For example, the Name parameter of Get-Help takes a String value, which
	is a text string, such as a single word or multiple words enclosed in
	quotation marks. 

		[-Name] <string>

	The .NET type of a parameter value is enclosed in angle brackets (< >)
	to indicate that it is placeholder for a value and not a literal 
	that you type in a command.

	To use the parameter, replace the .NET type placeholder with an object
	that has the specified .NET type.

	For example, to use the Name parameter, type "-Name" followed by a string,
	such as the following:

		-Name MyAlias

  Parameters with no values
  -------------------------
	Some parameters do not accept input, so they do not have a parameter
	value. Parameters without values are called "switch parameters" 
	because they work like on/off switches. You include them (on) or you
	omit them (off) from a command.
   
	To use a switch parameter, just type the parameter name, preceded by a hyphen.

	For example, to use the WhatIf parameter of the New-Alias cmdlet, type the following:

		-WhatIf

  Parameter Sets
  --------------
	The parameters of a command are listed in parameter sets. Parameter sets
	look like the paragraphs of a syntax diagram.

	The New-Alias cmdlet has one parameter set, but many cmdlets have multiple
	parameter sets. Some of the cmdlet parameters are unique to a parameter set,
	and others appear in multiple parameter sets.

	Each parameter set represents the format of a valid command. A parameter
	set includes only parameters that can be used together in a command. If
	parameters cannot be used in the same command, they appear in separate
	parameter sets.

	For example, the Get-Random cmdlet has the following parameter sets:

		Get-Random [[-Maximum] <Object>] [-Minimum <Object>] [-SetSeed <int>]
					[<CommonParameters>]

		Get-Random [-InputObject] <Object[]> [-Count <int>] [-SetSeed <int>]
				 [<CommonParameters>]

	The first parameter set, which returns a random number, has the Minimum
	and Maximum parameters. The second parameter set, which returns a randomly
	selected object from a set of objects, includes the InputObject and Count
	parameters. Both parameter sets have the Set-Seed parameter and the common
	parameters.

	These parameter sets indicate that you can use the InputObject and Count
	parameters in the same command, but you cannot use the Maximum and Count
	parameters in the same command.

	You indicate which parameter set you want to use by using the parameters
	in that parameter set. 

	However, every cmdlet also has a default parameter set. The default parameter
	set is used when you do not specify parameters that are unique to a parameter 
	set. For example, if you use Get-Random without parameters, Windows PowerShell
	assumes that you are using the Number parameter set and it returns a random number.

	In each parameter set, the parameters appear in position order. The order of
	parameters in a command matters only when you omit the optional parameter names.
	When parameter names are omitted, Windows PowerShell assigns values to
	parameters by position and type. For more information about parameter position, 
	see about_Parameters.


  Symbols in Syntax Diagrams
	The syntax diagram lists the command name, the command parameters, and the 
	parameter values. It also uses symbols to show how to construct a valid
	command.

	The syntax diagrams use the following symbols:


	-- A hyphen (-) indicates a parameter name. In a command, type the hyphen
	 immediately before the parameter name with no intervening spaces, as
	 shown in the syntax diagram.

	 For example, to use the Name parameter of New-Alias, type:

		 -Name 

	-- Angle brackets (<>) indicate placeholder text. You do not type the
	 angle brackets or the placeholder text in a command. Instead, you replace
	 it with the item that it describes. 

	 Angle brackets are used to identify the .NET type of the value that
	 a parameter takes. For example, to use the Name parameter of the New-Alias
	 cmdlet, you replace the <string> with a string, which is a single word or a
	 group of words that are enclosed in quotation marks.

	
	-- Brackets ([ ]) indicate optional items. A parameter and its value can be
	 optional, or the name of a required parameter can be optional. 
 
	 For example, the Description parameter of New-Alias and its value are
	 enclosed in brackets because they are both optional. 
 
		 [-Description <string>]
	 
	 
	 The brackets also indicate that the Name parameter value (<string>) is
	 required, but the parameter name, "Name," is optional. 

		 [-Name] <string>


	-- A right and left bracket ([]) appended to a .NET type indicates that
	 the parameter can accept one or multiple values of that type. Enter the 
	 values in a comma-separated list.

	 For example, the Name parameter of the New-Alias cmdlet takes only 
	 one string, but the Name parameter of Get-Process can take one or 
	 many strings.

		New-Alias [-Name] <string>

			 New-Alias -Name MyAlias

		Get-Process [-Name] <string[]>

			 Get-Process -Name Explorer, Winlogon, Services
			 

	-- Braces ({}) indicate an "enumeration," which is a set of valid values
	 for a parameter. 
 
	 The values in the braces are separated by vertical bars ( | ). These bars	 
	 indicate an "exclusive or" choice, meaning that you can choose only
	 one value from the set of values that are listed inside the braces. 

	 For example, the syntax for the New-Alias cmdlet includes the following
	 value enumeration for the Option parameter:

		-Option {None | ReadOnly | Constant | Private | AllScope}

	 The braces and vertical bars indicate that you can choose any one of
	 the listed values for the Option parameter, such as ReadOnly or AllScope.

		-Option ReadOnly



  Optional Items
	Brackets ([]) surround optional items. For example, in the New-Alias 
	cmdlet syntax description, the Scope parameter is optional. This is 
	indicated in the syntax by the brackets around the parameter name 
	and type:

		[-Scope <string>]


	Both the following examples are correct uses of the New-Alias cmdlet:

		New-Alias -Name utd -Value Update-TypeData
		New-Alias -Name utd -Value Update-TypeData -Scope global


	A parameter name can be optional even if the value for that parameter is 
	required. This is indicated in the syntax by the brackets around the 
	parameter name but not the parameter type, as in this example from the 
	New-Alias cmdlet:

		[-Name] <string> [-Value] <string>


	The following  commands correctly use the New-Alias cmdlet. The commands 
	produce the same result.

		New-Alias -Name utd -Value Update-TypeData
		New-Alias -Name utd Update-TypeData
		New-Alias utd -Value Update-TypeData
		New-Alias utd Update-TypeData


	If the parameter name is not included in the statement as typed, Windows 
	PowerShell tries to use the position of the arguments to assign the 
	values to parameters.


	The following example is not complete:

		New-Alias utd


	This cmdlet requires values for both the Name and Value parameters.


	In syntax examples, brackets are also used in naming and casting to 
	.NET Framework types. In this context, brackets do not indicate an 
	element is optional.



SEE ALSO
	about_Parameters
	Get-Command
	Get-Help