private string GeneratePrefix()
{
string genPrefix = "p" + (_nsTop - 2).ToString("d", CultureInfo.InvariantCulture);
if (LookupNamespace(genPrefix) == null)
{
return genPrefix;
}
int i = 0;
string s;
do
{
s = string.Concat(genPrefix, i.ToString(CultureInfo.InvariantCulture));
i++;
} while (LookupNamespace(s) != null);
return s;
}