deriv LSK ETT STT aSTA ALPH OLDHOMEPAGE NEWHOMEPAGE
The sounds J ञ् m म् G ङ् N ण् n न् usually follow the WYSIWYR principle.
However, when those sounds are followed by a /savarNa nasal or stop, there are two ways of spelling them, the old style (medieval) and the new style (proffesorial).
In the medieval spelling, the twenty-five sound combinations nt nth nd ndh nn mp mph... are invariably spelled as Mt Mth Md Mdh Mn Mp Mph, and the letter combinations Mt Mth Md Mdh Mn Mp Mph are invariably read aloud as nt nth nd ndh nn mp mph etc.
Explained this way, the rule looks crazy. But it makes sense when you know that M ं in Indian alphabets is written as a dot. This way of spelling saves ink, time, and, when reading bad typography, also much pain.
Since one or two centuries ago, Sanskrit paNDits and professors have slowly come to agree that the above spelling rule must be replaced with the following —
When the sound J ञ् m म् G ङ् N ण् n न् comes from replacing a padafinal m म् by first monusvAraH and then anusvArasy..., write your sound with the letter M ं, as if anusvArasy... had not worked. Otherwise, write it as J ञ् m म् G ङ् N ण् n न्.
In practice this boils down to:
Write the sound nt न्त् as M ंt त् if the n न् sound is the last letter of a /pada that ended in m म् and was changed by the optional rule anusvArasy.... Write all other nt न्त् sounds as nt न्त्. If you don't know if the n न् in parantapa परन्तप or in sandhiH सन्धिः is at the end of a /pada or not, ask the nearest paNDita पण्डित.
See also spelling of zz SS ss.