Nota accusativi

Nota accusativi is a grammatical term meaning "denoting accusative case". It is generally applied to linguistic indicators of the accusative case. An example is the use of the preposition "a" in Spanish to indicate an animate direct object (the "personal a"): "Jorge llama a María".
Esperanto.
Officially, in Esperanto, the suffix letter ""n" is used to mark an accusative. But a few modern speakers use the unofficial preposition "na"" instead of the final "n".
- Mi havas domon.
- Mi havas na domo.
- I have a house. 
Hebrew.
In Hebrew the preposition אֶת "et" used for definite nouns in the accusative. Those nouns might be indicated by use of the definite article (ה "Ha" "the"). Otherwise, the object may be determined by a possessive pronominal suffix, by virtue of being a "nomen regens" within a genitive construction, or being a proper name.
To continue with the Hebrew example:
Ani ro'eh et ha-kelev. אני רואה את הכלב
"I see the dog."
Ani ro'eh et kalbi. אני רואה את כלבי
"I see my dog."
Ani ro'eh et kelev Dani'el. אני רואה את כלב דניאל
"I see Daniel's dog."
Ani ro'eh et Dani'el. אני רואה את דניאל
"I see Daniel."
On the other hand, "I see a dog" is simply "Ani ro'eh kelev." אני רואה כלב 
This example is obviously a specialized use of the "nota accusativi", since Hebrew does not use the nota accusativi unless the noun in question is definite.
Japanese.
In Japanese, the particle "を" (pronounced "お" o) is the direct object marker and marks the recipient of an action.
Toki Pona.
In Toki Pona, the word "e" is used to mark accusative.
Other languages.
Nota accusativi also exists in Armenian, Greek and other languages.
In other languages, especially those that indicate case grammatically, there is usually a separate form (for each declension if declensions exist) to indicate the accusative case. The nota accusativi should not be confused with such case forms, as the term "nota accusativi" denotes a separate particle indicating the accusative case.