Line	Description
======= =======================================================================

?C:	Comments for #defines

?D:	Set default value for variable

	?D:osname=''

?F:	Defines what files are created by this module

?H:	Defines the part to be included in the generated config_h.SH

	To get #ifdefs in config_h.SH, you'll need strange constructs like

	?H:?%<:@if USE_SITECUSTOMIZE
	?H:?%<:#ifndef USE_SITECUSTOMIZE
	?H:?%<:#$usesitecustomize     USE_SITECUSTOMIZE               /**/
	?H:?%<:#endif
	?H:?%<:@end

?I:	Include

?INIT:	?

?L:	Library

?LINT:	tell what is to be expected extern and what is changed

	?LINT:define fieldn
	?LINT:extern CONFIG_H
	?LINT:change CONFIG_H
	?LINT:use PERL_CONFIG_SH

?M:	Magic

?MAKE:	symbol list: dependency list [+optional]

	This is the first dependency line. The first "symbol list"
	should list all the symbols built by this unit (i.e. whose
	value is computed by the shell section of the unit). Symbols
	should be space separated. If a defined symbol is for internal
	use only and should not appear in the generated "config.sh"
	file, then it should be preceded by a '+' (not to be confused
	with optional dependencies defined hereafter).
	The second part of the list (after the middle ':') is the unit
	dependency.  It should list all the needed special units, as
	well as all the symbols used by the shell implementation. If
	a symbol is nedded but its configuration value is not critical,
	it can be preceded by a '+', in which case it is called a
	conditional dependency: its corresponding unit will be loaded
	if, and only if, that symbol is otherwise really wanted;
	otherwise the default value will be used.

?MAKE:	<tab> command

	There can be one or more command lines following the initial
	dependency lines.  Those commands will be executed when the
	unit is wanted to load them into "Configure".
	Note that the leading <tab> character is required before the
	"command".

?O:	Obsoleted?

?P:	Public

?RCS:	free text

	To be used for RCS comments, at the top of the unit.

?S:	symbol_name (obsolete symbol list)]:

	Introduces a shell symbol. This first line names the symbol,
	optionally followed by a list enclosed between parenthesis and
	giving the obsolete equivalent. Those obsolete symbols will be
	remapped to the new "symbol_name" if the -o option is given to
	"metaconfig".

?S:	any text, for "Porting/Glossary"

	Basically a comment describing the shell symbol, which will be
	extracted by "makegloss" into the Glossary file.

?S:	.

	Closes the shell symbol comment.

?T:	What variables are used as temporary variables

?V:	Visible?

	?V:fieldn

?W:	Wanted

?X:	any text

	General purpose comments. May appear anywhere in the unit but must be
	left justfied. For RCS comments, please use the ?RCS: comment form.

?Y:	layout

	Declare a layout directive for this unit. That directive may be one
	of the strings "top", "default" or "bottom" (case does not matter,
	recommended style is to spell them out uppercased). If omitted,
	"default" is assumed.

	This directive is only required if you wish to force a unit at the
	top or the bottom of the generated "Configure" script, as unit
	dependencies permit it. Important questions may thus be forced
	at the beginning. Within the same layout class, units are sorted
	alphabetically with two special cases for d_* and i_* units, forced
	respectively at the top and bottom of their classes (but these
	should belong to the default class).

	It you force at the top a unit whose dependencies require all the
	other unit to precede it, you achieve nothing interesting. Therefore,
	that directive should really be used to increase the priority of
	some interactive units that do not depend on many other user-visible
	symbols, like path-related questions.

	?Y:TOP

lines can be made conditional (see Config_sh.U)

@if d_portable
:
:
@end