3.1. Standards
It is well documented that biodiversity data originating from integrative
biodiversity research is very heterogeneous (Bowker, 2000).
Consequently, enormous effort has been invested in developing standards
for data and metadata to improve their exchange and dissemination
(Meng, 2005). We classify data heterogeneity into five classes
of standards, according to Halevy (2005): technical, syntactic, structural,
semantic and data model standards. It is often impossible to assign
concrete standards to only one of these classes, since they
include specific components related to different classes. Nevertheless,
our discussion follows this classification, as summarized in Table 2.
The first column reports the heterogeneity type. The second column
provides the type of standard necessary to overcome the heterogeneity
in question, while in the third column a typical operation is listed
that is enabled after the standard is implemented.