Moed Katan, Chapter Three, Mishnah Three
Writing was not nearly as common of a skill in the time of the mishnah as it is now. Indeed, most people could probably not write, and if they could, they could write only simple things. Since writing was not common it was considered a professional skill. Hence it was generally forbidden on the festival. Our mishnah lists exceptions. These were allowed because they were of immediate necessity. I will explain each type of document.
1) They may write the following documents during the festival:
2) Betrothal of women [documents], divorce documents and receipts, wills of a dying person, bequests and prosbols; evaluation certificates and orders for support, documents of halitzah and of repudiation [of marriage] and arbitration records; decrees of the court and correspondence.
Betrothal of women [documents]: This refers to all sorts of documents connected to marriage, either arranging the betrothal and its economic elements (tannaim) or a document used to effect betrothal itself. In such a document the man would write, Behold you (or your daughter) are betrothed to me. Note that kiddushin (betrothal) can take place during the festival, but marriage may not. Therefore, ketubot, marriage documents, are not included in this list.
Divorce documents: Gittin. This is the document that a husband writes to his wife. Divorce is permitted on the festival.
And receipts: The creditor writes to the lender stating that he has received the money. This may also refer to a case of divorce, where a woman writes a receipt to her husband upon receiving the marriage settlement (her ketubah money).
The will of a dying person: Wills, which must be written and executed while the person is alive, are obviously not something that can be put off, especially when they are written by a dying person, the case to which our mishnah refers.
Bequests: A document transferring a present from one person to another.
Prozbuls: These documents allow a persons loans to carry through the Sabbatical year. If they are not written, then the loan is annulled in the sabbatical year.
Evaluation certificates: Documents which evaluate a debtors possessions so that the appropriate amount may be collected by the creditor.
And orders for support: These documents allow a widow to sell her dead husbands property in order to provide for herself.
Documents of halitzah: Halitzah is the refusal of levirate marriage. A woman might need this document to prove that she had been released and was free to marry another man.
And of repudiation [of marriage]: A minor girl whose father has died may be married off by her mother or brother. When she reaches majority age she may repudiate the marriage and have it annulled. She would need this document to prove that she had repudiated the marriage and was allowed to marry another man without having been divorced.
And arbitration records: Certain court cases would begin by the litigants choosing judges. These records would prove which judges had been chosen.
Decrees of the court: Documents recording their decision.
And correspondence: According to the Yerushalmis interpretation of this clause, it refers to simple letters of correspondence. In those days sending mail would have been quite difficult. It was not always easy to find someone going to the place where one wanted to send a letter. If such a person was found on the festival one was allowed to write a letter because the opportunity would be lost later. A different (and later interpretation) is that this clause refers to letters written to the government. Only such letters are permitted on the festival because they are of a greater need than simple letters of friendship.