@1
'Show' is the inverse command to 'Hide' and replaces the
current increment's short representation (the text "[...]"
in the case of a text representation, and a small dashed
rectangle in the case of a grafical representation) by its
full representation (right-mouse-button selection of the
current increment may be used to activate this command).

To redisplay suppressed and therefore unselectable optional
placeholders one has to apply 'ShowPlaceholders' to the
placeholder's father increment.

-->     'Hide', 'ShowPlaceholders', 
     'ShowAll', 'HidePlaceholders', 
@2
'Hide' is a presentation oriented command and may be used
to replace the current increment's full representation by
its short representation. Placeholders for optional parts
of a document don't have a short representation but will
completely disappear upon the application of this command.

To redisplay invisible and, therefore, unselectable place-
holders one has to apply 'ShowPlaceholders' to the place-
holder's father increment. 

For all other types of increments 'Show' is the inverse 
command to 'Hide'.

-->     'Show', 'ShowPlaceholders', 
     'ShowAll', 'HidePlaceholders' 
@3
'ShowPlaceholders' redisplays all invisible and, therefore,
unselectable placeholders for optional parts of the document
which are children of the current increment. 

-->  'Show', 'Hide', 'ShowAll', 
     'HidePlaceholders' 
@4
'HidePlaceholders' suppresses the representation of all 
placeholders for optional parts of the document which are 
children of the current increment. 'ShowPlaceholder' is
the inverse command for rediplaying these placeholders.

-->  'Show', 'Hide', 'ShowAll', 
     'ShowPlaceholders' 
@5
'ShowAll' redisplays the full representations of all
descendants of the current increment (with the exception
of optional placeholders).

-->  'Show', 'ShowPlaceholders', 
     'Hide', 'HidePlaceholders'
@6
'OpenWindow' creates a new presentation of the currently
selected (sub-) graph. This new presentation has the same
underlying representation structure as its master presen-
tation. Therefore, both presentation have the same current
increment etc.
