The data of the inventories appears in an integrated system: the incipits, mode (including transpositions), liturgical use, sigla and leaf numbering are displayed in identical format in all databases. Sources, feasts and liturgical functions are given in abbreviated form; their solution can be found in the corresponding databases. Alongside with the complete sources, we also use their survived fragments, which are distinguished from their mother codex by the abbreviation “(fragm.)” attached to the sigla. In addition to the accurate descriptions, the source database provides bibliographies of their traditional publications, monographs and catalogues, as well as links to their digital facsimiles and/or inventories. Thus, researchers and interested users are able to study side by side the images, source indices and selected chants in modern transcription, and place them in a synoptic system of melodic variants built from the repertory of other sources, while learning  about the literature and background resources.

The structure of the databases is not uniformed, as different chant genres can be identified using different features and data points. Beside the basic information that appears for all genres, we provide genre specific information for each specific genre or genre group: while the liturgical assignation of the office antiphons is determined by the hour and their position in the hour next to the feast, in the case of hymns the description of the hour is sufficient, and for mass chants and processional antiphons only the name of the feast is required. The numerical code in the numerus column has different meanings in different genres. In the catalogue of office antiphons, the numbers define the place of the chants in the system of musical typology: this corresponds to the type numbers developed by László Dobszay and Janka Szendrei, published in the Monumenta Monodica Medii Aevi V. (László Dobszay–Janka Szendrei, Antiphonen. Monumenta Monodica Medii Aevi 5. Kassel – Basel: Bärenreiter Verlag, 1999, vols. 1–3.). In the repertory of hymns the numerus follows the liturgical order of the chants: it proceeds according to the liturgical assignation of the main melody, starting with the hymns of the psalter, continuing with the hymns de tempore and de sanctis (proprium de sanctis and commune sanctorum). The numbers at the genres of cantus missae and cantus aliorum rituum represent a simple numerus currens following the alphabetical order of chants, without any additional musical or liturgical meaning.

The database and transcription of the hymns have further unique features: in the database a separate column presents the number of syllables per line of the strophes (Syllables), the closing cadence of the lines (Cadence), and the number of (related) melodic variations in the works of Benjamin Rajeczky (Melodiarium Hungariae Medii Aevi I, Ip, RajMel), and in the hymn edition of Bruno Stäblein (Monumenta Monodica Medii Aevi I. Hymnen, StMel). Beside the sigla of the sources in a second column, the traditions where each melodic variant belongs are given.

One of the most important yields of our website is the publication of chant melodies in modern transcription. These are published in a synoptic arrangement: the melodies are displayed together with their variants. The selected main melody is at the top, the further variants are below this, with added visual distinction, where the parts matching the main melody are drawn in a lighter colour, and the parts deviating from it appear in the normal colour (black).

We used the „modernized Messine-German notation” traditionally accepted in the Hungarian chant research, using the fonts guidohu.ttf and gui6+.ttf customized by János Bali and Gábor Kiss. This system is the most similar in structure to the Central European, including Hungarian Gothic notations used in late medieval plainchant sources. It depicts well the separate neume groups and the inner articulation of melodies, while being effortlessly and clearly readable for the musicians accustomated to the modern five-lined staves.

The appearance of the office antiphons is slightly different. In this case the publication is based on the databases of the formerly published MMMAe volume, prepared by the Department of Early Music History of the Institute for Musicology. According to the method used for these databases we presented only the variants in the synoptic melodic order without a visual colour difference.

The scores of more melismatic genres of the cantus missae and cantus aliorum rituum are given in two different ways: the simple presentation is followed by a second picture with grids to facilitate the orientation and comparative analysis. The grids separate the melodic units, and make the musical process more articulated and manageable.

The table of each melody can be enlarged and downloaded as an image.

In the text transcription the normalized Latin orthography has been used. Errors in sources, including misplaced clefs resulting in melodies a third out of mode  and faulty transpositions have been left untouched, though the user is warned by the „ms.” mark. Voids caused by accidental wear of the source (lacunae) are marked with #, the deliberate omission of a melody or part of the text with Ø. If a chant occurs more than once in a source, we indicated the second (or third) occurrence by an apostrophe attached to the siglum. The asterisk (*) attached to the feast, hora, function refers to their hypothetical state.