In Dutch, the process was already underway around the 12th century, which made it one of the earliest languages to be affected. In written documents of the 13th century, long vowels in closed syllables are generally written by doubling the vowel or by adding "e" or "i". In open syllables, only a single vowel was written regardless of whether the vowel was originally short or originally long, suggesting that length was implicit there. Early Middle Dutch still had long consonants, which closed the preceding syllable and prevented lengthening. Once the lengthening had occurred, the consonants began to lose their distinctive length, and vowel length once again became distinctive in open syllables.