Example of how you can build a complex regex on multiple lines with comments.

gistfile1.txt

$pattern = @'
  ^ # Beginning of the line
  # Get the hostname
  (?<hostname>
    # We have a DC name in the first 3 to 5 character
    (?<datacenter>.{3,5})
    - # Literal dash
    # etc etc
  )
  $ # End of the line
'@
$options = [Text.RegularExpressions.RegexOptions]'IgnorePatternWhitespace'
$regexMatch = [regex]::Match($HostName, $pattern, $options)

Oh that's neat, so all the literal white spaces get ignored thanks to the regex options, and I assume that also ignores new lines which is what lets you spread that across multiple lines? And \s or \ or \n wouldn't be ignored because they're explicitly part of the pattern?

Exactly. If you need a # you gotta escape it, but other then that it can help with readability.