great thanks jcl, cleared a lot of things up for me.

only a few left:

a) Does zorro execute run() for a bar with no tick structs in backtest or is it skipped?
b) What does zorro return when asked for price() for a specific minute it does not have a tick struct for, does it return null, an error or simply price() for the previous or next available tick struct? e.g if I try to use timeoffset to get an opening or closing price of an exchange what happens if there is no tick struct for that bar?
c) Do indicators skip bars with no tick structs or use last price received?