Several of the services Domus Merceris provides to Ordo Hermei are notarial. Perhaps the most well-known example occurs during declarations of Bellum Magum, but Domus Merceris provides notarial services in many ways. Conventum registration is sometimes thought of only in terms of correspondence, but in some Tribunalia, registration of a conventum with Domus Merceris may be the only record of its existence.

Other examples include declarations of inheritence, passing of a discipulus from one magus to another, and registration of vis sources. This last example, known as perscriptio vis in Hermetic Latin, has developed over the centuries into a set of formal processes. Although Domus Merceris tends to follow these defined processes throughout Ordo Hermei, some Tribunalia may interpret their value differently, and some Tribunalia have specific Leges Peripheriae that require modifications.

Perscriptio Locorum
The most basic form of registration consists of noting the location of the vis source, and the Art or Arts of vis that may be gathered. In this basic form of registration, no mention of the method of gathering is necessary, although in some cases may be alluded to in the description of the source.

Perscriptio Praxeos
Some magi may want to be more thorough in describing a particular vis source, and detail the specific method used to gather the vis. This may be necessary to avoid legal complications in some Tribunalia, or may simply be desired to forestall "accidental" gathering from a vis source.

Adnotatione Obsignata
Some magi desire to place a claim on a vis source without divulging anything at all about it. Domus Merceris offers a general type of notarial service in which a sealed document, known as a textus adnotatus obsignatus, is placed under seal. When this process is applied to registration of a vis source, it is termed an adnotatione obsignata, a notation under seal. In this case, any information about the vis source is recorded by the maga or conventum involved, sealed within some container or envelope, and then given to Domus Merceris. A representative of Domus Merceris, with at least two other witnesses, records the date, name of the maga or conventum, and a brief summary of the context, such as "record of a vis source in Tribunal Helvetiae."

it is customary to specify the Tribunal, as otherwise it may not be accepted as evidence in some Tribunalia. Tribunalia vary in the degree to which primacy of claim may be established through adnotatione obsignata, but in most it is sufficient to establish claim of a source when it is revealed, although rarely sufficient to convict another of depriving a sodale of magical resources.