# Remember the below is your friend in browsing through fields
Get-IshTypeFieldDefinition | Out-GridView

# Retrieving the System field that holds this information
$ishObject = Get-IshPublicationOutput -IshObject $ishObject -RequestedMetadata (Set-IshRequestedMetadataField -Level Version -Name FISHPUBCONTEXT)

# Printing the information
[xml]$context = $ishObject.fishpubcontext_version_value
# <?xml version="1.0" encoding="utf-16"?>
# <features>
#   <feature name="BLUETOOTH" value="Y" />
#   <feature name="GAMES" value="DJ" />
#   <feature name="GAMES" value="SNAKE" />
#   <feature name="GAMES" value="WATERRAPIDS" />
#   <feature name="GPRS" value="Y" />
#   <feature name="HEADSET" value="Y" />
#   <feature name="LOUDSPEAKER" value="Y" />
#   <feature name="MODEL" value="330" />
# </features>

# Preferably changing xml with proper XmlDocument functions to keep it valid/welformed like for example switching HEADSET from Y to N
$context.SelectSingleNode("features/feature[@name='HEADSET']").Value='N'

# Beware that there is only very basic validation on this field
Set-IshPublicationOutput -IshObject $ishObject -Metadata (Set-IshMetadataField -Level Version -Name FISHPUBCONTEXT -Value $context.OuterXml)