V.O. (Virtual Observatory) services are services based in the protocols defined by the Virtual Observatory. These services allow you to retrieve catalogue's data and images using V.O. compatible applications like TOPCAT, Aladin, ... (see V.O. Applications for astronomers)
MUDEHAR-DR1 - TAP Table Access Protocol
Table Access Protocol offers more flexible access to data tables. It allows you to retrieve catalogue data using as input a query in Astronomical Data Query Language (ADQL), which is basically a standardised version of SQL.
Read more about ADQL.
Simple Cone Search Service offers the simplest access to astronomical catalogues. It allows you to retrieve catalogue data on objects within a given radius around a specified location. Viewed in 3D, the radius defines a cone of space.