A small RichText markup class that matches a regex for a trailing 's' suffix and sets left margin to 0. It derives from RichTextBase and is annotated with a RichTextPanel attribute supplying the regex pattern.
[RichTextPanel( @"(?<=[\d\]])s\b" )]
public class RichTextSuffixS : RichTextBase
{
public override float? MarginLeft => 0f;
}