When creating a complex model, it can be very useful to see at a glance which components are influencing, and which are influenced by, the component you are looking at. This is particularly useful if you have a model spread over a very large diagram with ghosts used extensively to reduce the clutter of influence arrows. It is also very useful for debugging a running model - if you are looking at a component which seems to have the wrong value, it is useful to be able to jump to the values that are influencing that component to see where the error is creeping in.
Simile provides two mechanisms for following influences, one focused on the diagram and the other on the search mechanism.
Highlighting upstream/downstream
Normally, the selection is shown in blue, and the links to and from the selected area in dark green. There is also a set of highlit components, normally shown in light green (though all these colours are customizable, see "customizing desktop appearance"). The highlit components include the ghosts of components in the selection, and components whose ghosts are in the selection. But it can be modified to also include components influencing or influenced by those in the selection, at up to two steps away in either direction.
To enable highlighting of more components, select one of the last two entries of the desktop's View menu, 'Highlight Back' or 'Highlight Forwards'. Each of these has entries for One or Two functions, as well as the default setting of bases or ghosts only. Once this is done, components in the specified relation to the selection will be highlit immediately whenever a selection is made.
Searching for related components
This method causes the model diagram to scroll to show the relevant components, which is convenient for very large models. Make your selection in the normal way, then hit the 'Find' button as described in the Searching section. At the top of the dialogue that appears are three buttons, 'Components influencing selection', 'Components equivalent to selection' and 'components influenced by selection'. Hitting any of these buttons will start the search immediately; other fields in the search dialogue are ignored. One result is selected at a time, as for other searches, and the diagram scrolls if necessary to place the selected result at the centre. Since each result becomes a new selection, when you reach the one that is along the path you are following, you can immediately open a new search dialogue to continue searching from that point.