Okay I'll do my best. As I'm sure you know, India has its own rich tradition of linguistics and linguistic analysis going back to Panini and, before him, certain of the Vedangas. In Europe as well we have our grammatical traditions generally inherited from classical grammars of Latin and Greek. I can't really talk about those very much, but I bring them up because sometimes the way we might look at something in a schoolroom - whether we're studying a foreign language or our own - may not correspond exactly to the way we look at things in modern, international, academic linguistics. And that's totally fine because modern linguistics is trying to take a very rigorous, (more) scientific approach that (although it has borrowed traditional concepts and traditional terminology) applies more universally and takes account of more languages. Whereas in a schoolroom we're not necessarily trying to keep our fingers on the latest technical linguistics research, we're trying to teach people to read and write and spell and communicate. So I make no comment on how Gurmukhi spelling may be taught to foreign students of the language, or to children in India, I will talk only from the point of view of modern linguistics. Although in modern linguistics too there are times where people may not agree on definitions or classifications or how a particular phenomenon should be interpreted. Phonetics and phonology, in my experience, seem to be particularly open to interpretation. For example, the term 'retroflex' is defined by Wikpedia as
A
retroflex,
apico-domal, or
cacuminal (
/kæˈkjuːmɪnəl/)
consonant is a
coronal consonant where the tongue has a flat, concave, or even curled shape, and is articulated between the
alveolar ridge and the
hard palate.
Note the three choices of tongue shape and a nice wide window of possible positions.
Leaving that aside.
You are quite correct,
gemination is the correct word for lengthening a consonant. You give a perfect example. In ਪੱਤਾ
pattā the
t is held for longer - it takes longer to say - than the
t in ਪਤਾ
patā. In Gurmukhi this is indeed marked by the
addhak as you say.
Turning now to nasalisation. Consider the word ਮੈਂ
maiṁ. In this case we have a nasalised vowel, the vowel is pronounced with some of the air flowing through the nose giving a distinctive sound.
In a word like ਪਿੰਡ
piṇḍ, what we have is a nasal consonant
ṇ before the following
ḍ. Thus ਪਿੰਡ
piṇḍ is equivalent to ਪਿਣਡ. In modern linguistics terminology, we say that the
ṭippī represents a nasal consonant that is "homorganic" (pronounced in the same place) with the following consonant. Thus, while in ਪਿੰਡ
piṇḍ, the
ṭippī represents a ਣ
ṇ, in ਸਿੰਘ
siṅgh it represent a ਙ
ṅ. This generally would be considered a consonant, not a vowel. The
i in
piṇḍ, and
siṅgh may be slightly nasalised, simply on account of occurring just before a nasal consonant, just like the
a in ਅਨਾਰ
anār might be slightly nasalised, but my understanding at least is that that would usually be considered incidental. Now there is an important difference between these two phenomena - the nasalised vowel and the nasal consonant homorganic with the following consonant. I don't know if it's easy to illustrate in Punjabi, but it's very easy in Hindi. मँगवाना
mãgvānā should, theoretically, be pronounced with a nasal vowel and no clearly discernable ङ sound (as in si
ng). Theoretically, it should sound different to गंगा = गङ्गा =
gaṅgā, which should have a clear consonant sound. Some speakers may not make this distinction, or may not notice, I can make no comment on that, but अँग and अंग are theoretically different.
Now, in the case of ਲੰਮੀ
lammī what we have (so I have been told) is the equivalent of गंगा = गङ्गा. We have the nasal consonant homorganic with the following consonant. So in this case, the
ṭippī represents
m, just as it does in ਕੰਬਲ
kambal (I believe this means 'blanket', but I know almost no Punjabi, so perhaps this isn't really used; I know it is in Hindi). For this reason, we have here a double, or geminated
m, which is why my books at least tell me
Note that addak is not used to geminate m and n.