ExportDXF/ExportDXF/DrawingInfo.cs

using System.Text.RegularExpressions;

namespace ExportDXF
{
    public class DrawingInfo
    {
        private static Regex drawingFormatRegex = new Regex(@"(?<jobNo>[345]\d{3}(-\d+\w{1,2})?)\s?(?<dwgNo>[ABEP]\d+(-?(\d+[A-Z]?))?)", RegexOptions.IgnoreCase);

        public string JobNo { get; set; }

        public string DrawingNo { get; set; }

        public string Source { get; set; }

        public override string ToString()
        {
            return $"{JobNo} {DrawingNo}";
        }

        public override bool Equals(object obj)
        {
            if (obj == null)
                return false;

            return obj.ToString() == ToString();
        }

        public override int GetHashCode()
        {
            return ToString().GetHashCode();
        }

        public static DrawingInfo Parse(string input)
        {
            var match = drawingFormatRegex.Match(input);

            if (match.Success == false)
                return null;

            var dwg = new DrawingInfo();

            dwg.JobNo = match.Groups["jobNo"].Value;
            dwg.DrawingNo = match.Groups["dwgNo"].Value;
            dwg.Source = input;

            return dwg;
        }
    }
}