I have been away, so a backlog of things to do!
I'll try to get around to your queries as soon as I can, but in the meantime, have you looked at:
http://www.irseexam.co.uk/attachment.php?aid=29
I think this should provide some answers; however basically brackets are "to hold expressions together". There are two main reasons where they are used;
1) to avoid "ambiguity" where there is an expression of the form: A, B or C.
Colloquially this means A or B or C but mathmatically it doesn't!
It actually means "either both A AND B must be true or alternatively C must be true" for expression to be satisfied.
If you want it to mean "A must be true AND also either of B or C must be true", then you need brackets- viz: A, (B or C)
2) Where a single expression spans adjacent columns in a Control Table. To be honest when two column are cleary related, such as track occupied and the "for time", then they can be omitted but it is always safer to put in. An alternative presentation links the entries in the two columns by dashes- this was perhaps more common when CT's handdrawn than when CAD is used. Indeed if we need to link entries in multiple columns or non-adjacent columns then we often use both the brackets and the dashes.
I'll try to get around to your queries as soon as I can, but in the meantime, have you looked at:
http://www.irseexam.co.uk/attachment.php?aid=29
I think this should provide some answers; however basically brackets are "to hold expressions together". There are two main reasons where they are used;
1) to avoid "ambiguity" where there is an expression of the form: A, B or C.
Colloquially this means A or B or C but mathmatically it doesn't!
It actually means "either both A AND B must be true or alternatively C must be true" for expression to be satisfied.
If you want it to mean "A must be true AND also either of B or C must be true", then you need brackets- viz: A, (B or C)
2) Where a single expression spans adjacent columns in a Control Table. To be honest when two column are cleary related, such as track occupied and the "for time", then they can be omitted but it is always safer to put in. An alternative presentation links the entries in the two columns by dashes- this was perhaps more common when CT's handdrawn than when CAD is used. Indeed if we need to link entries in multiple columns or non-adjacent columns then we often use both the brackets and the dashes.