  This paper presents an approach for metadata reconciliation, curation and
linking for Open Governamental Data Portals (ODPs). ODPs have been lately the
standard solution for governments willing to put their public data available
for the society. Portal managers use several types of metadata to organize the
datasets, one of the most important ones being the tags. However, the tagging
process is subject to many problems, such as synonyms, ambiguity or
incoherence, among others. As our empiric analysis of ODPs shows, these issues
are currently prevalent in most ODPs and effectively hinders the reuse of Open
Data. In order to address these problems, we develop and implement an approach
for tag reconciliation in Open Data Portals, encompassing local actions related
to individual portals, and global actions for adding a semantic metadata layer
above individual portals. The local part aims to enhance the quality of tags in
a single portal, and the global part is meant to interlink ODPs by establishing
relations between tags.
