 Increasingly, however, it became the ambition of linguists like the Neogrammarians to formulate general and exceptionless rules of sound change that would account for all the data (or as close to all the data as possible), not merely for a well-behaved subset of it.One classic example of Proto-Indo-European ' → Proto-Germanic is the word for 'father'.Proto-Indo-European (here, the macron marks vowel length) → Proto-Germanic (instead of expected ).