Encoding parameter accept numeric Ids and name of registered code pages

[iSazonov]

Issue Details

PR PowerShell/PowerShell#7636 enhance the encoding transformation attribute:

• to allow numeric Ids of registered code pages (like -Encoding 1251)
• to allow string names of registered code pages (like -Encoding "windows-1251")

Affected cmdlets:

gcm -ParameterName Encoding

CommandType     Name                                               Version    Source
-----------     ----                                               -------    ------
Cmdlet          Add-Content                                        6.1.0.0    Microsoft.PowerShell.Management
Cmdlet          Export-Clixml                                      6.1.0.0    Microsoft.PowerShell.Utility
Cmdlet          Export-Csv                                         6.1.0.0    Microsoft.PowerShell.Utility
Cmdlet          Export-PSSession                                   6.1.0.0    Microsoft.PowerShell.Utility
Cmdlet          Format-Hex                                         6.1.0.0    Microsoft.PowerShell.Utility
Cmdlet          Get-Content                                        6.1.0.0    Microsoft.PowerShell.Management
Cmdlet          Import-Csv                                         6.1.0.0    Microsoft.PowerShell.Utility
Cmdlet          Out-File                                           6.1.0.0    Microsoft.PowerShell.Utility
Cmdlet          Select-String                                      6.1.0.0    Microsoft.PowerShell.Utility
Cmdlet          Send-MailMessage                                   6.1.0.0    Microsoft.PowerShell.Utility
Cmdlet          Set-Content                                        6.1.0.0    Microsoft.PowerShell.Management

Full list supported code pages we can found in
https://github.com/dotnet/corefx/blob/master/src/System.Text.Encoding.CodePages/src/System/Text/EncodingTable.Data.cs

Version(s) of document impacted

• Impacts 6.next document
• Impacts 6 document
• Impacts 5.1 document
• Impacts 5.0 document
• Impacts 4.0 document
• Impacts 3.0 document

Reason(s) for not selecting all version of documents

• The documented feature was introduced in selected version of PowerShell
• This issue only shows up in selected version of the document

[sdwheeler]

This is a duplicate of or related to the following issues:

• Docs needed for 'Allow numeric Ids and name of registered code pages in '-Encoding' parameters' #3027
• Update the default/acceptable values for Encoding parameter in v6.0 #2000

[iSazonov]

It is new functionality. It is not dup but related mentioned issues.

[joeyaiello]

We should document this by adding a line or two to the parameter description of each cmdlet and/or about_Encoding to say that this parameter accepts codepage values. about_Encoding should link to [the .NET documentation on Encoding.CodePage