In addition to the predefined parameters volau, volad,
length and lanes, volume-delay functions could, up to Release 8,
only access application specific function parameters which were stored in
the link user data items ul1, ul2 and ul3.
Similar, turn penalty functions could only access application specific
parameters stored in the turn user data items
up1, up2 and up3.
Release 9 introduces three new extra function parameters for both volume-delay and turn penalty functions, which can be used --in addition to the already available user data parameters-- to access application specific function parameters.
For volume-delay functions
the keywords for the new extra link parameters
are el1, el2 and el3;
for turn penalty functions
the new extra turn parameters are accessed using the keywords
ep1, ep2 and ep3.
In contrast to the existing user data item keywords,
these new keywords do not a priori imply the use of a specific link or turn
attribute, but they represent abstract parameters at the function
definition level. These will only become associated with actual link
or turn attributes when a scenario is being prepared for an auto assignment.
At this time, module 5.11 checks the functions for occurrences of
any of these extra function parameters and will only then associate
the function keyword with a user defined attribute of the corresponding
type. This attribute is then used for providing the parameter values
during the subsequent auto assignment.
Any extra link attribute or link user data item can be assigned to
el1, el2 and el3,
and any extra turn attribute or turn user data item to ep1,
ep2 and ep3.
The user specifies the attributes to be used for the extra function
parameters either directly in the dialog of module 5.11, or
via the new menu commands
el1=, el2=, el3=,
ep1=, ep2= and ep3= which each define
a default attribute name for the corresponding extra function parameter,
applicable to all scenarios.
In the latter case, module 5.11 attempts to use these default
attributes if possible, and only intervenes interactively if
a default attribute is not available.
All currently active default settings for the extra function parameters
can be displayed with the new menu command efp.
The new extra function parameters can be used in two ways: For applications which use very complex functions, they provide three new additional parameters that allow the inclusion of more link specific information into the function evaluation. For applications which do not need more than three application specific parameters, replacing the fixed user item keyword by extra function parameters may be beneficial, since it allows a more flexible use of the functions. Functions coded with extra function parameters are easier to exchange between different applications and within a single application they facilitate switching between different value sets for the same function parameter.