There are three forms of Hymmnos:

• Hymmnos Extract
• Hymmnos Words
• Hymmnos Spells

Hymmnos Extract is a name for the chants that control Towers. It is this branch of Hymmnos that has the power to directly control Ar tonelico. However, this power generally requires authorization before a Reyvateil can make use of it; this authorization is typically granted based on a Reyvateil's "Hymn Code" (note: third-generation Reyvateils do not have Hymn Codes, though they are still connected to towers).

An example Hymn Code is "EOLIA_ANSUL_ARTONELICO"; it uniquely identifies a specific β Reyvateil.

Reyvateils with access to Hymmnos Extract may perform great feats ranging from gravity manipulation to weather control, earthquakes to environmental orchestration, and much more.

Hymmnos Words, informally known in the Third Era as "Song Magic", are mainly used for everyday tasks and combat. These are formed from the richness of a Reyvateil's heart, which makes them highly versatile. As a Reyvateil allows more feelings and emotions to flow through her heart, the possible variations of Hymmnos Words increase, making this a Hymmnos branch with limitless potential.

Hymmnos Spells are chants that, instead of drawing form from a Reyvateil's heart, make use of pre-defined Hymmnos strings, much like Hymmnos Extracts. This fixed nature leads to one of the most significant features of this branch of Hymmnos: it can be used by humans, not just Reyvateils. Accordingly, the majority of Hymmnos Spells exist as a means of authentication and interaction with Towers.

Grammatically, Hymmnos Spells are identical to Hymmnos Words. the difference is that Hymmnos Spells are registered with a tower, so they have a pre-defined function. Intuitively, it follows that new Hymmnos Spells cannot be created by individuals because they would not be connected to tower functions.

This section attempts to explain the logical system of each type of Hymmnos.

While it may seem as though all three branches of Hymmnos are fundamentally the same -- speak a chant -> something happens -- there are significant differences between them.

Hymmnos Spells are different because they are not limited to use by Reyvateils. However, the difference between the other two branches is buried deeper in their natures: Hymmnos Words are based entirely on an individual Reyvateil's heart and experiences, while Hymmnos Extracts are highly structured, inorganic patterns.

▼ Invoking Hymmnos Extract

Those familiar with Hymmnos theory may have realized that Hymmnos Extract does not directly reflect any emotional desires within the Reyvateil using it. Though it employs H-waves, these waves carry only a clear, plain message that tells the Tower to act.

In all cases, the H-waves of a Reyvateil should be able to reach their destination, carrying her collected thoughts. However, this does not mean that the chant will always result in exactly what the Reyvateil wants, particularly if the Reyvateil made a mistake, omitted a sentiment, or does not feel confident in the chant she sang.

The most difficult Hymmnos Extracts to use are also the most uncomfortable for the Reyvateil to accept, as the feelings with which they were designed are conveyed directly to the recipient. If the Reyvateil cannot handle the feelings, she may be entirely unable to use the Hymmnos Extract.

To overcome this, "stories" that alter the Reyvateil's emotional state may be used as a form of shock-absorber to allow her to download Hymmnos Extracts; this is often the fastest way to encourage compatibility between a Reyvateil and a foreign program. When downloading, if there is still a conflict between the Reyvateil and the Hymmnos Extract, the Reyvateil may refuse to allow the download to complete or the downloaded program may be unusable.

EXEC_PAJA/. is a chant registered with a Tower that runs a function of the system; it is communicated using a Reyvateil's feelings (H-waves).

Technically, the Hymmnos chant was downloaded (memorized) and the Reyvateil (daughter (of the tower -ed)) sang it -- what the Reyvateil has done is much the same as how a device controller reads the data from a DVD.

To explain this in more technical terms, the Reyvateil's song, which sent a message via the wave-spectrum of her feelings (H-waves), was generated by a CPU-like component that used a bus to access her memory, allowing for control over things like the bandwidth and resolution of the retrieved data (which, perhaps, accounts for differences between identical Hymmnos Extracts sung by different Reyvateils -ed). A table that summarizes this relationship is presented below.

Expressed in terms of contemporary technology, H-waves are like program instructions and D-waves are used to show the results on a screen.

The H-waves associated with Hymmnos Words, in some cases, may be omitted without affecting the results of a chant; because the sound of such Hymmnos may resonate with Sound Stones, the singing itself may lead to the intended result without the intervention of a Tower. (And, given the nature of Hymmnos Words, there is no reason why the related H-waves would necessarily be meaningful) It follows, given that humans can use them, that Hymmnos Spells do not involve H-waves. Hymmnos Extracts, however, offer the Reyvateil no freedom with regard to H-wave generation.

Hymmnos Extract relies on foreign feelings, which denies the singer the ability to use her own discretion to control the flow of H-waves. This is best explained by contrast: consider the Hymmnos Words of EXEC_HYMME_LIFE_A:W:S/., as sung by Aurica; when she begins, she subconsciously determines the spectrum and flow of the H-waves she emits. However, when she sang the Hymmnos Extract EXEC_LINCA/., the H-wave flow required to establish the connection was pre-determined and, therefore, beyond her control. From this example, you should observe that singing Hymmnos Extract requires a Reyvateil to be able to meet Extract-specific minimum levels of flow and spectrum.

Unfortunately, these demands have the potential for tragedy: it should be apparent that Hymmnos Extract places extreme demands upon the powers of a Reyvateil, much moreso than any other form of invoked Hymmnos. Second-generation Reyvateils (β-Reyvateils) generally have no problems meeting the requirements of these chants: being, fundamentally, clones of the Origin, their powers all satisfy identical minimum standards, allowing for the neat separation of Hymmnos Extract into two categories: Origin-exclusive and general-purpose for the "pure-blooded β-types". (Note: In the Second Era of Sol Ciel, pure-blooded β-types were enhanced, providing some with powers that rivaled, and possibly even surpassed, those of Origins) The problem arises with the third generation, which offers no minimum guarantees regarding abilities. Because of this, those of the third generation who would invoke Hymmnos Extract place themselves at great risk of dying under the stress of the demands placed upon them.

It should be noted, however, that third-generation Reyvateils, lacking Hymn Codes, are not able to use restricted Hymmnos Extracts.