The gloss line matches each sequential morph of T by an L2 unit placed below it. For this to work properly, T must fulfill some conditions:

Rule 2. The L1 text should be represented in such a form of writing which is amenable to the indication of morphological boundaries and to an interlinear representation and word-by-word association of its morphological gloss.
If traditional L1 orthography does not support this, there may be a line of morphophonemic representation beneath the original L1 text line. This is then the text line T matched by the morphological gloss.

1. In general, the most appropriate representation of T for display of its morphological structure is a morphophonemic representation in the Latin alphabet. A good morphophonemic representation steers a middle course as far as allomorphy is concerned: phonologically conditioned allomorphy is resolved (ignored), morphologically conditioned allomorphy is not resolved (is rendered). Apart from its morphological transparency, a morphophonemic representation has the added advantage of being a purely linguistic representation which can be expanded by special symbols without hurting L1 aficionados' esthetic feelings.

   A morphophonemic representation is not only the best basis for displaying the morphological structure. It may also be coupled with a syntactic analysis, since it represents grammatical units.

2. The text orientation (or writing direction) of L1 and L2 must be the same. If L2 uses some occidental alphabet, its orientation will be left-to-right. If L1 has a different orientation, the T line to be glossed must be rearranged. This is generally achieved by representing T in some transcription using the Latin alphabet. Unless there are specific reasons to use some conventional transcription, this is also the occasion to provide a morphophonemic representation of T. Additionally, T may be shown in the original script, as in . The mapping of its units onto units of the transcription may be achieved, inter alia, by superscripted numbers.

   .	𒀀	𒉿	𒈝
   Akkadian	a	pi	lum
   	awīl-um
   	free.man-NOM
   	free man

3. Similar considerations apply if the initial representation of T blurs the morphophonemic structure. This applies both to phonetic or phonological representations and to most traditional (including non-alphabetic and even alphabetic) orthographies. Whenever appropriate, such a representation should be coupled with an additional line in morphophonemic representation, which is then the reference line for the gloss.
4. Otherwise, if there is only one T line in a non-morphophonemic representation, it may be impossible or inadvisable to expand it by such special symbols as indicate morphological structure. In this situation, the morphological gloss is reduced, too, esp. by application of Rule 23.