Panini deals with both external and internal sandhi. As a majority of Panini's rules are concerned with the formation of correct words, a large number of sutras discuss internal sandhi.
External sandhi is joining of two words occuring in continuous utterance i.e it occurs across the word boundary and is found in the formation of compounds, phrases and sentences.
Internal sandhi is found in the combination of a stem and a suffix. It occurs within a word and such type of sandhi is found in derivation of finished words such as nominal declension and verbal conjugation. Sandhi operation, in general, takes place involving the final letter of the starting word and the initial letter of the following word.
Major types of Sandhi process
Four major types of sandhi process can be identified. They are Substitution (aadesa), addition(aagama), loss or deletion (lopa) and no-change (prakrtibhaava)
Substitution ( A:dðS: - adesha)
Substitution rules form a majority of Panini's rules. The rules mention replacing element, morpheme or a word. Substitution of two elements by one is called ekadesa and the single substitute replaces both the preceding and succeeding phonemes (purva parayoh).The rule describing this is : Ek:ð y:N:ec:
Addition ( A:g:m: - Agama)
A new element is introduced between two elements involved in sandhi. The additional element may be an initial increment or an infix.p:Øö + k<ekl:H = p:Øösk<ekl:H ( pum + kokilaH = pumskokilaH ) Loss or deletion ( l:<p: - lopa )
An element occuring in a stem disappears while another element is introduced. Panini explains the disappearance lopa as replacement. There are several instances of such loss in the derivation of Sanskrit words.herH + sPÙret: = hersPÙret: (hariH + sphurati = harisphurati - visarga dropped)
No change (p:Òkáet:B:av: - Prakrtibhaava)
No change takes place when two words occur in continuous utterance in certain cases.
hri + Ot:> = hri Ot:> (harI + etau = harI etau)
Panini also classifies sandhi rules as vowel sandhi, consonant sandhi and visarga sandhi depending on whether the words ends in vowel, consonant or visarga.Formulation of rules in internal sandhi
When a suffix is added to a
stem or a root both the stem and the suffix undergo modifications. These
modifications are explained in morphophonetic rules, mentioning the stem or suffix which
undergo changes specifying the context.