using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
 
public class Test
{
	public static void Main()
	{
		var s = "GET_LIST 1000 10001 10002";
   	var pattern = @"^GET_LIST(?:\s+([A-Za-z0-9]{4,10})){0,100}$";
    	var results = Regex.Matches(s, pattern)
		.Cast<Match>().SelectMany(p => p.Groups[1].Captures
			.Cast<Capture>()
			.Select(t => t.Value)
		)
		.ToList();
            Console.WriteLine(string.Join(", ", results));
	}
}

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