The editor should also be integrated with the modeling tools, so when a symbol is
altered, existing models update immediately. Seeing a symbol in several places in a
model, possibly with different scales and zooms, gives a much better impression of
how well it works than seeing it once in the symbol editor, often zoomed to make
editing easier. This once again emphasizes the importance of having the
metamodeling and modeling tools integrated in the same environment.
Role Symbols The symbols for roles are something of a special case, because
they must rotate with the line over which they are displayed. Tools without a true
concept of role will often offer just a few simple choices of arrowheads, but even a
cursory look at existing modeling languages will reveal far more variation. Since
vector graphics can be rotated with relative ease, it seems simplest to allow the same
freedom to roles as to other symbols.
Text elements are somewhat problematic in role symbols. Most modeling
languages have found that text works best when displayed horizontally.Aslight angle
or incline to text along a role line is no great problem, providing the font can be
rendered suitably smoothly (still a challenge in many cases). Anything over 45 of
incline tends to render models much harder to read, with the user having to crick her
neck back and forth at a different angle for each role.
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