using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;

public class Test
{
	public static void Main()
	{
		var text = "[MYLINK ID=\"1234\" URL=\"http://m...content-available-to-author-only...e.com\" TEXT=\"Website link\"]";
		var pattern = "\\[MYLINK\\s+ID=\"([^\"]*)\"\\s+URL=\"([^\"]*)\"\\s+TEXT=\"([^\"]*)\"]";
		var replacement = "<a href=\"$2?id=$1\">$3</a>";
		var result = Regex.Replace(text, pattern, replacement, RegexOptions.IgnoreCase);
	   	Console.WriteLine(result);
	}
}