I GUESS it'd be difficult to overstate just how important the Land Reform Bill which is currently working its way through the Scottish Parliament is going to be for keeping the farming industry afloat.

Covering not only issues like community right to buy and land registration, it's also going to bring into effect a whole raft of changes to the agricultural holdings act - and with it huge ramifications for both farm tenants and landlords.

Now, other than some of the more unscrupulous land agent firms and the lawyers who have probably made a killing out of it, I doubt if there would be many who felt the job was a good-un when the repercussions of the last redrafting exercise finally emerged out of the other side of the round of legal shenanigans which it prompted.

I guess the 2003 holdings act, which so many have found wanting, is a mere infant to be superceded already in the statute book. But, in common with the current effort, it too was drawn up with the aim of building fairness into tenancy legislation.

Much to the detriment of its well-intentioned aims, though, the actual drafting of the 2003 act became a neglected side show, eclipsed by political posturing during the drafting of the bill which soon fizzled out when the spotlight of media attention was aimed elsewhere.

Sadly, as someone said, it looks like a case of déjà vu all over again as the current bill is being rushed through parliament - and similarly emotive media soundbites are once more thrusting huge bloated red herrings into the limelight.

This will detract attention away just when minds should be focused on ensuring that the crucial details of the new legislation make it fit for purpose.

The last time around, it was the flap over the absolute right to buy (ARTB) issue which floundered about, drawing all the attention - while doing little more than muddying the waters and detracting attention away from the core issue of getting the legislation properly nailed.

This time it looks like the beached whale thrashing around in the political shallows is set to be the issue of assignation.

For, while attention is focused on these tantrums around the low tide mark, there's a real risk that the lifeguard is ignoring the deeper waters which will be the sink-or-swim zone for virtually every tenant farming business in the years to come - the rent review.

And, even if you only dip a toe into these waters, you'll soon realise that without a secure life-belt of solidly constructed legislation we'd soon be 'not waving, but drowning'.

It's been well flagged up that the new rent review process will be based not on the rack-renting principle of 'comparables' (basically what some idiot is willing to pay for a similar unit) but, instead, on what at first appears to be the far simpler and fairer idea of the 'productive capacity' of the land.

One common mistake has been to make the obvious assumption that this means what's actually happening on the farm in question.

Way too simple, though. Instead, the highly complicated procedure for working out the productive capacity revolves around what a hypothetical 'Mr Average Tenant', working with what the landlord has provided, would be likely to glean from the land, buildings and other assets supplied.

But, while any value contributed to the farms returns by tenants' improvements will be discounted, on long-standing tenancies even figuring out what has been supplied by the landlord and what would count as improvements provided by tenants will be both difficult and contentious.

And, although there might be a broad agreement on the type of farming which goes on in any particular area, there is room for huge argument on the exact cropping patterns/stocking densities which could be used, an argument which might be simplified as to how often a tattie rent could be claimed off the ground.

But, even if yields and other measures of physical output can be calculated, how is agreement going to be reached on prices when swings in global markets can see wheat prices move by £10 a tonne in the course of a week?

Should we be using the price which grain, cattle, sheep or whatever has been making in the preceding years, in the year in which the review is carried out or what they might be over the three years until the next review takes place?

Of course, the price of the variable cost inputs will need to be factored in too - and agreed upon up front.

It looks like support payments will be included in the calculations - even if only for the reason that, as this week's farm income figures so pointedly showed, without them there would be virtually no rent charged on any farm in Scotland.

But they, too, are prone to exchange rate fluctuations - and, given the upcoming Brexit referendum, to a substantial degree of uncertainty over their future existence.

Labour and machinery required and supplied by the hypothetical tenant to work his hypothetical system will also need to be removed from the top line of the productive capacity calculation, as will all the other costs of running an effective farm business such as finance and bank charges.

Some have suggested this should even include the almost compulsory costs of paying a land agent to argue the case during rent reviews.

And, of course, there's formula for deciding exactly how the margin left is to be shared out between tenant and landlord.

So, make no mistake, there's going to be a whole sea of hassle ahead for tenants and landlords - but if the rules are properly drawn up there's a chance we might all make it to the shore alive.

But if the side-show distracts the attention of those drafting the bill, we're all sunk.