
The CDFwalk program allows direct access to related variable data
values.  The data values of up to 27 variables may be displayed at once
(the CDF can have more variables but only 27 may be viewed at any one time).
The data value for each variable at a given record/indices location within
the CDF conceptual view is displayed.  The user can ``walk'' from one
record/indices location to another sequentially (in any ``direction'') or
a particular record/indices location can be ``jumped'' to directly.  Variable
values may also be used to directly ``jump'' to a record/indices location.

The user interface to CDFwalk is contained on a
single screen which is divided into several fixed windows and
pop-up windows.  The Action Menu controls the execution of
the program. This menu allows you to ``walk'' through a CDF,
select a new CDF through which to ``walk'', browse online help, or
exit the program.  This menu may be displayed
at any time by entering Ctrl-F.  Use the up and down
arrow keys to highlight a choice in the Action Menu and
then enter a carriage return to execute that function.
Two very important windows are the Keypad Definition
and Message windows. They contain information on keypad
functionality and program status/error messages.

When CDFwalk is executed (and a CDF and/or directory is not
entered on the command line), you must first specify the
CDF through which you wish to ``walk''.  If you enter
a full disk/directory specification (without a CDF
name), all of the CDFs in the specified directory will
appear in a separate pop-up window.  Use the up and down
arrow keys to choose a CDF and then enter a carriage return
to ``walk'' throught that CDF.

After the input CDF is 
selected, the Record/Indices window appears.  The size of
this window depends on the dimensionality of the input CDF.
Vertically the window 
will contain one row for the record number
and one row for each dimension of the CDF.  
Horizontally, each line of the window contains three fields.
The first field contains a variable name, the second field
contains a data value for the variable, and the third field
contains a record number or dimension index. 

The variable selected for the record number line will be one 
that only varies from record to record (not varying along any
of the dimensions).  If more than one variable of that type
exists in the CDF, a pop-up window will be displayed containing
the list of varibles.
Select one of the variables keeping in mind that you will have an
opportunity to use it for positioning by value to a desired record.

The variable selected for each dimension line will be one
that only varys along the corresponding dimension (and
does not vary from record to record).
Again, if more
than one variable of that type exists in the CDF, a pop-up window
will be displayed to allow you to select the variable to use for
that dimension.  Keep in mind that you will be able to use it to
position by value to a desired index along that dimension.

After the Record/Indices window has been specified (which may
occur automatically), the Variable Values window will be
displayed.  It contains up to 27 variable names and the associated data values
for the record/indices shown in the Record/Indices window.

Initially the 
cursor will be positioned at the data value field of the 
record number line in the Record/Indices window.  You may 
now begin to ``walk'' through the CDF by using the right 
arrow to increment and the left arrow to decrement the 
record number.  Each time a new record number is specified
the data for each variable is updated in both the Record/Indices
and Variable Values windows.  If
the CDF contains many records, you may want to quickly 
advance to a desired record.  You may do this by entering
the i key (the cursor must be on the data value field).
CDFwalk enters an input mode and prompts
the value to which to advance.
If the exact value is not in the CDF for the variable, the 
record number is changed to correspond to the
closest possible value.  Another method
of advancing to a desired value is by entering Ctrl-P.
This will cause a pop-up window containing all of the
values for the variable to be displayed.  You may select the value 
desired as you would with any other pop-up window and CDFwalk
will automatically position the record number to the corresponding
value.

After positioning to a desired record (and the CDF is 
multi-dimensional) you may now wish to ``walk'' through the
dimension indices.  This is done by entering the up and 
down arrow keys to position the cursor to the desired dimension line.
``Walking'' through dimensions is done in the same way as
``walking'' through the record numbers.

You may also wish to ``walk'' through the CDF by
using the actual record number or dimension indice
rather than data values.  This is done by entering a carriage
return which causes the cursor to advance to the next field
(ie. from the data value field to the record number/indices field).
Entering Ctrl-H causes the cursor to move back to the
previous field.
``Walking'' through the CDF using the record number/indices fields
is the same as using the data value fields but with a few exceptions.
First, no Ctrl-P option is available with these fields.
Also, when in input mode, you may input either an absolute
record number/index to which to move or you may enter a relative
offset for the record number/index.  Prefixing the value with
a +/- will increment/decrement the record number/index by
that amount.

If the CDF contains more than 27 variables and a particular
variable is not currently displayed in the Variable Values
window, an option is provied to
scroll new variables into that window.  This is done by 
entering a v key.  A small pop-up window
is displayed in which you may use the up and down
arrow keys to scroll in or scroll out variables.  If the
CDF contains a very large number of variables, entering a
u or d key will display a new set of 27 variables (moving
up or down through the variables in the CDF).
When the desired set of variables is displayed, enter a carriage return
to continue ``walking'' thru the CDF.

When you are done ``walking'' through the CDF,
enter Ctrl-F to display the Action Menu.  You
may input a new CDF, resume ``walking'' through the current
CDF, read online help, or exit the program.
