System.Uri.CheckSchemeName C# (CSharp) Method

        public static bool CheckSchemeName(string schemeName)
        {
            if (((object)schemeName == null)
                || (schemeName.Length == 0)
                || !UriHelper.IsAsciiLetter(schemeName[0]))
            {
                return false;
            }
            for (int i = schemeName.Length - 1; i > 0; --i)
            {
                if (!(UriHelper.IsAsciiLetterOrDigit(schemeName[i])
                    || (schemeName[i] == '+')
                    || (schemeName[i] == '-')
                    || (schemeName[i] == '.')))
                {
                    return false;
                }
            }
            return true;
        }

        //
        // Static Registration methods
        //
        //
        // Registers a custom Uri parser based on a scheme string
        //
        public static void Register(UriParser uriParser, string schemeName, int defaultPort)
        {
            if (uriParser == null)
            {
                throw new ArgumentNullException(nameof(uriParser));
            }

            if (schemeName == null)
            {
                throw new ArgumentNullException(nameof(schemeName));
            }

            if (schemeName.Length == 1)
            {
                throw new ArgumentOutOfRangeException(nameof(schemeName));
            }

            if (!Uri.CheckSchemeName(schemeName))
            {
                throw new ArgumentOutOfRangeException(nameof(schemeName));
            }

            if ((defaultPort >= 0xFFFF || defaultPort < 0) && defaultPort != -1)
            {
                throw new ArgumentOutOfRangeException(nameof(defaultPort));
            }

            schemeName = schemeName.ToLowerInvariant();
            FetchSyntax(uriParser, schemeName, defaultPort);
        }