Aptai de misericordia is a very interesting institution of law that is specific to the Dubrovnik Republic. References to Aptai can already be found in 1272, in the Dubrovnik Statute. The term itself stands for a specific tribunal fee collected by the Rector. Later, the meaning of the term itself changed and aptai started to indicate a civil court proceeding in which that fee had to be paid. Finally, in the second half of the 14th century, the term aptai started to stand for a mode or process that was used to ensure the fulfilment of the debtor's obligation. That obligation was made, i.e., signed in the Chancellery, and it became official after the expiration of the deadline entered in the document. Based on the evidence, it is therefore clear that the entries in the books of the Aptai de misericordia had the power of a judgment and that there was no need to pursue further legal action against the debtor. The entries contain the following information: name and surname of the donor of the charity promissory note, name and surname of the recipient of the charity promissory note, and payment deadline. Valuable items nominated by the borrower to be mortgaged were also sometimes indicated, together with the details of instalment payments. In the margin, along with singular entries, data on debt repayment, were specified. Most of the records in this series follow this model: Jacobus d'Abram Pardo hebreus dedit aptaii de misericordia supra Vitum Michaelis, Andream Pasqualis Vuchotich, et Demetrium Mihailovich calceolarius presentibus simul et in solidum de ducati sexaquinta de g. totius summae (vol. 4, f. 14).

The series gives relevant data for the research of credit transactions of Dubrovnik Jews, who mostly are referenced in the documents of the series as donors, or providers of charity. All the Jews referenced to in this series were permanent residents of Dubrovnik. The first references to their names in the documents date to the end of the 16th century, and many more Jewish names can be found in the documents since the middle of the 17th century. The names of some members of Jewish families such as Abeatar, Abenun, Amadio, Azubi, Coen, Danon, Franco, Israel, Maestro, Oef (Ohev) and Tobi were recorded. Some of them very often cited as creditors, or those who lent money, and the names of Solomon Maestro, and a well-known Dubrovnik merchant Raphael Coen especially stand out among those names. Other Jews that should also be pointed out for their importance are two brothers: Jacob Coen de Herrera (Martin de Marchena), a brother of a famous Jew Abraham Coen de Herrera (Allonso Nuñes de Herrera). The records show also references to other Jewish people of that time, such as: Ambonetti, Ascoli, Asser, Baraffael, Bueno, Cagli, Campos, Coen, Costantini, Forte, Gaon, Levi, Levi Mandolfo, Luzzena, Maestro, Nachas, Navarro, Pappo, Pardo, Russi, Saralvo, Terni, Tolentino, Valenzin, Vitali.

The series contains data on various debts and other types of obligations of individual citizens towards the Republic, which were registered in the period from the middle of the 15th to the beginning of the 17th century.

The only reference to Jewish people in this fonds dates to 1503. Benedict Levi, Aron Alemanus and Abraham Alemanus confirmed in this document that they had received 126 and 3/4 of gold Venetian ducats from the Rector of the Dubrovnik Republic and the Minor Council as the equivalent of 130 ducats (gold coins) they had previously lent to the Dubrovnik archbishop John (de Sacchis) (vol. 1, f. 110).

The series mainly contains data on commercial credits, which were registered in the period from the end of the 13th to the beginning of the 19th century. The records include date of the credit agreement, name of the creditor, name of the borrower, amount of the credit, duration of the credit, and contractual clauses of the credit agreement. The interest amount is not entered. Those who wanted to take a loan and did not reside in the Republic, and still wanted to register the credit agreement at the Public Notary of the Republic, could do this through their legal representative.

The series is very important for researching business transactions of Jewish people in the Balkans and the Mediterranean, as well as for a possible historical reconstruction of their commercial network, especially since the period of the early 70s of the 16th centuries, when the Jewish population in Dubrovnik significantly increased. Some well-known and very prominent members of the local Jewish community are referenced to in the series, such as Aron Coen and Abraham Coen de Herrera (i.e., vol. 96, f. 20v). In general, the series refers to members of the Dubrovnik Jewish community such as Abenun, Coen, Danon, Lanciano, Maestro, Miranda, Oef. Some Jews who were referenced did not live in Dubrovnik, but, overall, all Jews who are referenced in the documents occur in both functions: as creditors and as borrowers. In an attempt to better understand the significance of this series for the overall history of the Sephardim, it is advisable to refer to the doctoral thesis of Benedetto Ligorio (Roma, Sapienza, 2017), in which the author analysed the existing archival data on credits referencing the Jewish population between 1560 and 1654. The analysis of Ligorio provides relevant data that prove that in most of these documents Christians (primarily Dubrovnik noblemen) were stated as creditors for Jewish people.