A worm that has infested your apple tree is likely the apple maggot. It can affect other fruits too. If you have your apple tree chopped down and chipped up into mulch, it may kill all or most of the apple maggots during the process.
If you ever have troubles with maggots, worms, or caterpillars eating your fruit, you can often send pictures or a live sample to your local Ag Extension office and they can help identify the problem. Predatory wasps can be effective against lots of different types of worms and caterpillars. Good luck!
Metadata schemata can be hierarchical in nature where relationships exist between metadata elements and elements are nested so that parent-child relationships exist between the elements. An example of a hierarchical metadata schema is the IEEE LOM schema, in which metadata elements may belong to a parent metadata element. Metadata schemata can also be one-dimensional, or linear, where each element is completely discrete from other elements and classified according to one dimension only. An example of a linear metadata schema is the Dublin Core schema, which is one dimensional. Metadata schemata are often two dimensional, or planar, where each element is completely discrete from other elements but classified according to two orthogonal dimensions.