A tie connects two consecutive notes of the same pitch and should not be mistaken for slurs that connect multiple notes for other reasons. This is necessary, among other things, if a note extends "over-the-barline", or "over-the-beat" to properly display the meter:
You enter the start connection with <9> , the end with <0> That choice for 0 and 9 is less strange than it seems at first glance; on most keyboards, these are the keys that also have the parentheses on them. If you enter the end connection at the second note, MusiCAD immediately searches for the previous note and if it has the same pitch, it is immediately provided with start connection.
In principle, ties are between notes of equal height, but in MusiCAD they can also be used for convenience between notes of different heights (in fact, not a connection but a slur, legato, articulation, stroke direction or phrasing).
A slur used as a tie in MusiCAD ALWAYS runs from note ball to note ball, and therefore always stays in the right place after transposition. 'True' ties start just after the note (or after any lengthening dot), and run until just before the next note. If you still want to have the binding noted as a slur you can change the display in the note properties menu: force as a slur. or <ctrl-0>
Connections that would become too short to remain legible are displayed by MusiCAD as slur. By spacing the notes further apart you can show the tie as such again. You specify the minimum distance for display as a tie in the layout dialog.
Ties are directly linked to the note (visible by ( on the status line).
The direction of connections (down or over) is basically determined by MusiCAD on the basis of note height and bow direction. If you want to see it differently, you can specify how it should be done with <shift-ctrl-> and <shift-ctrl-> (also note properties menu)