bioValidator is a free software that can be used to validate field data collection spreadsheets, assign unique identifiers to records and tag photos with data.
Data validation is based on a set of rules that are defined in an XML file. Each rule can be set to a level of "Error", which means that no downstream processing or PhotoMatching can occur, or "Warning" which means that this is an issue that can be fixed later and not critical for fixing immediately.
Tools for building validation XML files are forthcoming in later releases. Meanwhile, it is important to know that all XML rules files themselves are validated against an XSD schema document.