```common lisp
;;;; Copyright (c) 2014
;;;;
;;;;     Robert Strandh (robert.strandh@gmail.com)
;;;;
;;;; all rights reserved. 
;;;;
;;;; Permission is hereby granted to use this software for any 
;;;; purpose, including using, modifying, and redistributing it.
;;;;
;;;; The software is provided "as-is" with no warranty.  The user of
;;;; this software assumes any responsibility of the consequences. 

;;;; This file is part of the string module of the SICL project.
;;;; See the file SICL.text for a description of the project. 
;;;; See the file string.text for a description of the module.

(cl:in-package #:common-lisp-user)

(asdf:defsystem :sicl-string
  :serial t
  :components
  ((:file "packages")
   (:file "conditions")
   (:file "condition-reporters-en")
   (:file "utilities")
   (:file "copy")
   (:file "case-conversion")
   (:file "string")
   (:file "trim")
   (:file "comparison")))
```

Use package ASDF-USER for system definition.
user
```common lisp
;;;; Copyright (c) 2014
;;;;
;;;;     Robert Strandh (robert.strandh@gmail.com)
;;;;
;;;; all rights reserved. 
;;;;
;;;; Permission is hereby granted to use this software for any 
;;;; purpose, including using, modifying, and redistributing it.
;;;;
;;;; The software is provided "as-is" with no warranty.  The user of
;;;; this software assumes any responsibility of the consequences. 

;;;; This file is part of the string module of the SICL project.
;;;; See the file SICL.text for a description of the project. 
;;;; See the file string.text for a description of the module.

(cl:in-package #:asdf-user)

(defsystem :sicl-string
  :serial t
  :components
  ((:file "packages")
   (:file "conditions")
   (:file "condition-reporters-en")
   (:file "utilities")
   (:file "copy")
   (:file "case-conversion")
   (:file "string")
   (:file "trim")
   (:file "comparison")))
```
assistant