The base network editor, module 2.12, has undergone a major overhaul for
release 4.0. Since all changes are upward compatible with the previous
versions, switching to the enhanced version of this module should cause
no problem. However, in order to take advantage of the new features,
it is important to know that they are there and how they can be activated.
The command area has changed slightly - note the addition of the
TWO WAY LINKS command box in the link attribute section:
Let's now look at the enhanced functionality of the module:
a) Generalized functionality of "USE SAME DATA" flag
The command USE SAME DATA can now
be used after any operation: add, delete, modify, list. The attributes
of the element operated most recently on will take effect if the
USE SAME DATA is activated. These values are kept in separate
variables for
nodes and links, so that even when switching between tables, the old
"same values" remain usable. The letter "l" (for list) typed on the
USE SAME DATA box displays the current values. The letter "u" can
be used anywhere on the worksheet to activate USE SAME DATA - as
a quick alternative to pointing to the corresponding box. If a distance
has not been entered specifically, the ratio Euclidian distance vs. length
is preserved and will be used to compute length in USE SAME DATA mode.
Note that this feature allows very efficient
link splitting,
since the attributes no longer have to be transcribed manually.
When adding elements, it is now possible to partially disactivate
the USE SAME DATA status for some attributes.
In this case, the USE SAME DATA is overwritten for the chosen link or node
attributes selected by the appropriate boxes. The so selected attributes
have to be entered interactively, regardless of the USE SAME DATA command.
This is useful when adding many elements (nodes/links) which have common values
for some of the attributes, but others that differ. It is, thus, possible
to be prompted only for a chosen subset of attributes, using the USE SAME DATA
feature for all others.
b) Status display, Operations and Commands
On color terminals, the active command boxes are now colored red, so that the status can be read permanently, without the need to issue a status command. The status command remains, since it's still necessary for monochrome terminals. When used in color mode, the active status lights will momentarily switch to green, as they do now.
The state of the command area is
now preserved after an UPDATE PLOT. As a consequence, the "(*)"
for LINK, LIST and ALL DATA, as well as the
(*=DEFAULT) are no longer
useful and have been deleted from the command headings. At the very first
plot after the dialog, a STATUS operation is performed automatically to
indicate the default settings on a monochrome terminal (remember that on
color terminals the STATUS is now permanently visible).
Wherever applicable, the commands can be used as "toggles",
i.e. pointing on an inactive box will activate it, pointing on an active
box will inactivate it. This applies to: link/node attributes,
TWO-WAY LINKS and USE SAME DATA.
All operation and option boxes can now also be activated directly from within the editing window without the need to "travel" with the pointing device to the corresponding command box. This is achieved by typing the corresponding command letter on the keyboard, as follows:
OPERATION: OPTIONS:
"a" ADD "s" STATUS
"d" DELETE "n" NUMERIC INPUT
"m" MODIFY "u" USE SAME DATA
"l" LIST "g" UPDATE PLOT (*)
"r" RESTART
"q" QUIT
(*) The "g" will activate the UPDATE PLOT box and then
accept one further keystroke to indicate the kind of
graphic command (N=node numbers, L=node labels, W=window,
1-9=demarcations, M=manual mode, <space>=simple update).
The UPDATE PLOT box remains active as long as in
a graphic command mode (such as window or manual),
to give a visual indication that the work sheet
is not in normal operating mode.
c) Two-way Links
This addresses the need to perform
link operations (add, delete, modify) that apply to links in both
directions. If the identical link operation is to be performed also
on the return link (J - I), this can be indicated by entering the
J-node with a two-way character "=". While this mechanism applies
the two-way feature only locally to one single operation, there is
also a new command box labeled TWO-WAY LINKS in the link section
of the command area. If it is activated, all link operations are
performed in a two-way manner. The default state of this option
can also be set using a new module parameter. If a two-way operation
fails on the I-J part, an error message is issued and the J-I part
is not attempted; if an error is detected in the J-I direction,
an error message is issued, but the (already terminated) I-J operation
is not affected by this. The list operation is always performed in
one direction only - if the network is symmetric, the list operation
in reverse direction is redundant anyway.
d) Link Chaining:
Often, link operations are performed along a link chain or path. In the previous versions of the network editor, this resulted in the annoying need to input every node twice in a row: once as the end node of one link, then again as the starting node of the following link. This can now be avoided by entering the next J-node directly using a "J" character. In this case, the last entered J-node (if available) is automatically used as the I-node of the next link. In this manner, operations along a path can be entered with much less effort. This option can also be used when the two-way command box is active (note the the "J" and the "=" are mutually exclusive, since both are entered when pointing at the J-node of the link.