In the Beer Lambert Law (equation 3) the term IT/Io is called transmittance. This form of spectroscopy has a setup similar to the one used for Absorption. Reflectance spectroscopy is the study of light as a function of wavelength that has been reflected or scattered from a solid, liquid, or gas.
Definition of metadata: Data that serves to provide context or additional information about other data. For example, information about the title, subject, author, typeface, enhancements, and size of the data file of a ...
Metadata is  data about data. Two types of metadata exist: structural metadata and descriptive metadata. Structural metadata is data about the containers of data. Descriptive metadata uses individual instances of application data or the data content. The business metadata tell you what data you have, where they come from, what they mean and what their relationship is to other data in the data warehouse. 2  Business metadata may also serve as a documentation for the DW/BI system. 3  Users who browse the data warehouse are primarily viewing the business metadata.