In dtc-23-02-10.pdf, page 159 (pdf 170), add a new section 10.3.5 

10.3.5 FEEL Libraries

A library has a name, is defined in a namespace, and contains a list of function declarations. The syntax of a library is defined below:

library = 
	"namespace" , qualified name , ";"
        name , "{" , functions ,  "}" 
        ;

functions = 
	function , { ";" , function }

function =
	"function" , name, "(" , [ formal parameter { "," , formal parameter } ] , ")" , ":" , type
	;

where
- name is described in section 10.3.1.2, rule 25 
- qualified name is described in section 10.3.1.2, rule 18 
- formal parameter is described in section 10.3.1.2, rule 56 
- type is described in section 10.3.1.2, rule 52 
- name, qualified name and formal parameter contain only symbols that are classified as letters and digits in the Unicode standard.
- the libraries are uniquely identified by the namespace and library name pair.

The definitions of the FEEL libraries are platform-independent, they do not contain any information about the execution platform (e.g. Java). The discovery of the definitions of the libraries and the artifacts needed to execute the functions (e.g. Java jars or Python modules) are vendor-specific.

The functions defined in a library become visible in the scope of the evaluation (see 10.3.2.11) once they are imported in a DMN file with the import type https://www.omg.org/spec/DMN/EL/LIBRARY (see 6.3.3).

The functions defined in a library are invoked in the same way as the imported BKMs or Decision Services (e.g. prefix.f(a, b, c)).

For example, for the following library

      namespace org.omg.feel.stringUtil;

      stringLib {
        // Checks if str is empty ("") or null.
	function isEmpty(str: string) : Boolean ;
	...
        // The capitalized str, null if str is null
	function capitalize(str: string) : string
      }

once the library is imported with


    <import namespace="org.omg.feel.stringUtil"
                     name="myLib"
                     importType="https://www.omg.org/spec/DMN/EL/EXTENSION"
                     />


the function isEmpty can be invoked by myLib.isEmpty("abc").