In research into identities it needs to be determined, among other things, in which aspects groups distinguish themselves from other groups, and how people present themselves as members of a group. This goes for various types of family groups, as well as social strata and functions, and organisations such as guilds and monastic orders.

Researchers need to be able to judge the information provided by the sources as to its prevalence or rarity. Is a memorial representation with a Crucifixion and devotional portraits one of many, or are some of its iconographic aspects special? Does a foundation charter that details a family’s commemoration contain the usual stipulations, or does it deviate in certain ways? The answers to such questions can be found through a combination of broad comparative research and quantitative research on the one hand, and case studies on the other. See 1.5for an example of such research.

Researchers into the commemoration of the dead are presented time and again with a tricky challenge: the research materials have become dispersed, and sometimes their existence may even be unknown. The MeMO database therefore offers inventories with descriptions of objects and texts that fulfilled a function in memoria. The types of sources that have been included in the database are the following:

• Tomb monuments and floor slabs
• Memorial pieces (painted and/or sculpted artworks)
• Memorial registers (administrative and liturgical sources)
• Narrative sources that fulfilled functions in the commemoration of the dead

For further explanations see chapter 3 and chapter 4 of this introduction.

The inventory covers the area that is currently the Netherlands until 1580 (see map in chapter 6). Around that year the larger part of the Netherlands saw the change in the public religion from the catholic religion to what was then called the reformed religion. This change slowly but surely caused the end of the commemoration of the dead in its medieval form in these areas. Noord-Brabant, Limburg, parts of Gelderland and Zeeuws-Vlaanderen largely remained catholic, although the catholic and the reformed religion alternated with intervals until 1648.