5.2.2
Location of Java Classes
The request time Tag handler classes and the translation time TagExtraInfo classes are just 
Java classes.  In a Web Application they must reside in the standard locations for Java 
classes: either in a JAR file in the WEB INF/lib directory or in a directory in the WEB INF/
classes directory.
The previous rule indicates that a JAR containing a packaged tag libraries can be dropped 
into the WEB INF/lib directory to make its classes available at request time (and also at 
translation time, see Section 5.3.2).  The mapping between the URI and the TLD is explained 
further below.
5.2.3
Tag Library directive
The 
taglib
 directive in a JSP page declares that the page uses a tag library, uniquely 
identifies the tag library using a URI and associates a tag prefix that will distinguish usage of 
the actions in the library.
If a JSP container implementation cannot locate (following the rules described in 
Section 5.3.1) a tag library description for a given URI, a fatal translation error shall result.
It is a fatal translation error for the 
taglib
 directive to appear after actions using the prefix 
introduced by the 
taglib
 directive.
5.3
Tag Library Descriptor
The Tag Library Descriptor (TLD) is an XML document that describes a tag library. The 
TLD for a tag library is used by a JSP container to interpret pages that include 
taglib
directives referring to that tag library. The TLD is also used by JSP page authoring tools that 
will generate JSP pages that use a library, and by authors who do the same manually.
The TLD includes documentation on the library as a whole and on its individual tags, version 
information on the JSP container and on the tag library, and information on each of the 
actions defined in the tag library.
Each action in the library is described by giving its name, the class for  its tag handler, 
optional information on a 
TagExtraInfo
 class, and information on all the attributes of the 
action. Each valid attribute is mentioned explicitly, with indication on whether it is 
mandatory or not, whether it can accept request time expressions, and additional information.
Chapter 5
Tag Extensions
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