Announcement: The operation of NSDL has been transferred to ISKME's OER Commons (effective December, 2014) - Read the news release.
This documentation describes the policies, procedures, and services that existed while NSDL was operated by UCAR.
All metadata records in the NSDL are xml documents that are xml valid and and xml well-formed and must use one of the format described below. Each Xml principles are described and each metadata format is explained and is linked to a how-to page for more details on creating xml records in that particular format.
The NSDL can only take in metadata records that are well-formed, in the correct metadata format, and that are valid with respects to the format's schema. In order for an xml record to be well-formed, it must follow the guidelines of the W3 Consortium, such as correct capitalization, inclusion of both start- and end-tags, and proper nesting. A good tutorial for learning the basics of well-formed xml can be found at w3schools.com. Additionally, official documentation about the xml standard can be found at w3.org.
Xml records are valid when they comply with the metadata schema for the format they are written in. For example, all valid lar records must comply with the lar schema. The schema stipulates which fields must be present in lar metadata records, whether they can be used multiple times, whether they have a controlled vocabulary, etc. There are many xml editors which will check for valid and well-formed records
Many times, it will take some back-and-forth between a collection builder and NSDL support staff to get the metadata records correct. This is best done early in the process, before the collection builder invests a lot of time and effort creating many (possibly incorrect) records. Luckilly, since xml is text-based, it's a fairly easy process to email the information back and forth to get the metadata just right.