This article presents an approach for dealing with archaeological excavation data with its imperfection (imprecision). It introduces a new archaeological data model in PVL and extends it in Imperfect PVL. Since the beginning of the 1980's, the need of excavation data storage has appeared and some information systems devoted to archaeological data were deployed. The first database in Reims (France) was built in 1983. Urban excavation data should be considered according to the triplet time-space-function. Therefore, as same as spatiotemporal information, archaeological information system could be modeled using spatiotemporal modeling language such as PVL. In urban excavations, there are two principal studied spatial objects: the studied site and the archaeological entities that are present in an excavation site. Urban archaeological entity is structured over several spatial scales. At a more global scale an entity may be composed by some object representing a data at more local scale. Therefore, the information system may allow the storage of archaeological sites which are a composition of archaeological entities. An archaeological entity may aggregate archaeological entities. The scales of object are obtained by specializing archaeological entities. An archaeological entity has a spatial shape, a function (wall, oven, house, etc.), and the period of activity when the object was used with its function. The kinds of archaeological entities (different scales) handled by our model are stratigraphic units (US) which may contain artifacts); facts (aggregations of US); structures (coherent aggregations of individual archaeological); and building blocks (coherent set of entities at a higher level). In addition to these entities we will also consider the spatiotemporal documentation class. The documentation class allows storing the reference on entities, and it has a location and a date. In our model, archaeological entities and sites are considered as areas while the geometric type representation of the artifacts and documentations is the point. To represent the dating, archaeological entities and the artifacts are represented by a pictogram indicating a time interval whereas the documentation class which has an instantaneous existence is represented by a pictogram indicating its appearance date. In addition to their spatial and temporal characteristics, these classes except the site class have descriptive characteristics like the dimension. The archaeological entity is linked to the material class that provides a description of all the materials composing it. The artifacts have also their own description in terms of materials. Nevertheless, by querying about the past, archaeological information is by essence imperfect and its quality should be taken into account from the information system modeling to the analyses. An adaptation of a classic GIS modeling language is used in this article in order to model archaeological data and its imperfection. Thus, data imperfection may be identified, characterized and memorized and queryable into an archaeological GIS. From this modeling, a new database approach could be developed in order to store data and their imprecision.