When not handled by decomposition into C + CV, CCV syllables are handled by combining the two consonants. In the Indic scripts, the earliest method was simply to arrange them vertically, but the two consonants may merge as a conjunct consonant letters, where two or more letters are graphically joined in a ligature, or otherwise change their shapes. Rarely, one of the consonants may be replaced by a gemination mark, e.g. the Gurmukhi "". When they are arranged vertically, as in Burmese or Khmer, they are said to be 'stacked'. Often there has been a change to writing the two consonants side by side. In the latter case, the fact of combination may be indicated by a diacritic on one of the consonants or a change in the form of one of the consonants, e.g. the half forms of Devanagari. Generally, the reading order is top to bottom or the general reading order of the script, but sometimes the order is reversed.