Helpful C# method to get value between two string identifiers

GetAllValuesBetweenIDs.cs

/// <summary>
/// Generic function to pull out string values between two identifiers
/// </summary>
/// <param name="document"></param>
/// <param name="startVal"></param>
/// <param name="endVal"></param>
/// <returns></returns>
private static List<string> GetAllValuesBetweenKeys(string document, string startVal, string endVal)
{
    string temp = document;
    List<string> result = new List<string>();
    int currentLocation = 0;
    while (temp.IndexOf(startVal) != -1)
    {
        string temp2 = temp.Substring(currentLocation);
        if (temp2.IndexOf(startVal) == -1)
        {
            break;
        }
        string afterVal = temp2.Substring(temp2.IndexOf(startVal) + startVal.Length);
        if (afterVal.IndexOf(endVal) == -1)
        {
            break;
        }
        string val = afterVal.Substring(0, afterVal.IndexOf(endVal));
        result.Add(val);
        currentLocation = temp2.IndexOf(endVal) + endVal.Length;
        temp = temp2;
    }

    return result;
}