The PMap for each field group in the sequence may or may not be present in the encoded message. We can define it using the following approach.
If at least one field within the template sequence requires a PMap bit, then a PMap must be present at the beginning of each field group. Otherwise, no PMap will be present for the field group.
In cases where no PMap is present, application code can use an empty PMap object (which will always return 0 for the next presence bit) for each field group.