The two notated melodies share a similar overall melodic organization for the first three lines: ab, cb, cd. The final half-line is more similar in profile to the opening half line in RoA 123 than in Pa lat. 1154. This melodic patterning within the first three lines of the strophe is shared with two of the notations for a text of the same basic poetic structure, Ad caeli clara (Pa lat. 1154 and Pa lat. 8318, first strophe). The melodic profiles indicated for the first halves of lines two and three demonstrate close parallels: the clives (2b) on syllables two and three correspond, and at the fifth syllable both notations record an extended descent. Correspondences are less precise elsewhere in the strophe.
While a similar melodic organisation may be observed in the two recorded melodies, this does not by itself support any notion of direct transmission. The shared strategies for texts with parallel verse structures nevertheless suggest some degree of association and encourage consideration of more varied models of transmission. Such models might incorporate the notion of something akin to a ‘best solution’ for melodic organisation for this particular verse structure: the ab, cb, cd e patterning, for example, could be said to be a particular effective way of projecting the strophe through melody by means of patterning around its mid-point (abc, bcd), followed by a separate final half-line (e). A process of structural melodic imitation akin to the process of imitation by which the texts of Ad caeli clara and Gloriam Deo share the same verse structure but differ in content might also be imagined. 

In Roma 123, Gloriam Deo precedes the troped Introit for the third Mass for Christmas Day (Puer natus) and is introduced by the rubric: Incipit versus in nativitate domini ante eps. The stipulation for performance «ante episcopum» suggests that the event at which Gloriam Deo was sung was stationary rather then processional, and was possibly associated with the ritual reception of the bishop (Baroffio, as reported in Llewellyn, A Paulinus of Aquileia versus, p. 99). Whatever the nature of the ritual in which Gloriam Deo was sung, the later appearance of Gloriam Deo in a liturgical book following its earlier transmission in late ninth-century verse collections such as Paris lat. 1154 might initially seem to represent a later adaption of the song to liturgical use. Shorter versions of the text are nevertheless already found in such manuals of devotional material as Verona 88 and 90, many of whose verse texts are found elsewhere with notation and almost all of which may be presumed to have been sung. The possibility that this raises is that the melody notated in Roma 123 is not one that arrived in Italy from the North, but a version of a melody (or set of melodic procedures) that had circulated in association with this text in Italy since at least the late ninth century and possibly earlier.

Only the first eleven strophes were copied by the text scribe of Roma 123 with an understanding that notation would be added, as witnessed by

the practice of leaving space for the melisma at the fifth syllable in line one and spare use of abbreviations. Shortened versions of the poem (none of which are identical, for details see the text entry for Gloriam Deo) are also copied in the devotional manuals Verona 90 and Verona 88, as well as in Napoli IV. G. 68. The full text, however, is copied in the verse collections Paris lat. 1154 and Bruxelles, Bibliothèque Royale 8860-8867. The implication of these formats is that a shortened version of the poem was sung when Gloriam Deo was performed in a liturgical context.