In the tractate of Shabbat the Mishna lists 39 prohibited tasks. These are the activities one is forbidden to do on Shabbat, and are based on the actions necessary for the erection of the Mishkan, and its contents. Despite their importance, any task involved in the setting up of the Mishkan is forbidden on Shabbat.
The 39 categories of work which were performed in and for the Mishkan are called the AVOT MELACHA, the fathers or primary categories, since they are the foundation, the original source for all secondary types of Melacha which are similar and derived from them. These similar types of work are called Toladot, descendants, just like parents and children. But from aspect of their being forbidden, there is no difference between an Av or its Tolada, for both are equally forbidden by the Torah. In sum:
Av Melacha
is an act which was done in the construction of the Mishkan.
Toladais an act which resembles an Av in its nature and end product.
For example, Planting is an Av Melacha, but watering is a Tolada because it encourages the growth of the plant.
11 tasks linked with the preparation
13 tasks linked with the preparation of the priestly
9 tasks linked with writing.
3 tasks linked with preparing a fire.
2 tasks linked with building.
1 prohibition is linked with removing items and carry