!ASIS Issue #093
!topic  Nil_Line equal line with zero length?
!reference  ASIS 95-20.1
!from  Sergey Rybin  98-02-24
!keywords  Line Is_Nil empty string
!discussion

Clause 20.1 (type Line) and 20.13 (function Is_Nil) requires
clarification on the difference between an empty line and a Nil_Line.
Are Nil_Line and a line with zero length the same thing?

!resolution  Accept.
!date 98-04-30
!Notes

The following clarification has been added to clause 20.1:

-- Nil_Line is the value of an uninitialized Line object.

Add to clause 20.13, function Is_Nil:

--
-- A Line from a Line_List obtained from any of the Lines functions
-- will not be Is_Nil even if it has a length of zero.

Add to clause 20.18, function Length, to clause 20.24, function
Line_Image, to clause 20.25, function Non_Comment_Image, and to
clause 20.26, function Comment_Image:

-- Raises ASIS_Inappropriate_Line if Is_Nil (The_Line).