BBC Scotland news website political reporter Andrew Black answers some of the main questions surrounding what will change.

What is an Availability Status Code?

ASCs replaced their predecessor, Guarantee Exception Codes, in 2003 and when applied to patients, strips them of their waiting time guarantee.

Patients are placed on these codes if they are, for example, unable to attend appointments or are not fit enough for treatment.

Although patients remain on hospital waiting lists, they are not covered by the maximum waiting time guarantee and, in a number of cases, end up waiting longer for treatment.

How will the new system work?

Health Secretary Nicola Sturgeon has announced that all patients who need to see a specialist at an outpatient clinic, or who need hospital treatment, will receive treatment within the maximum waiting time limits.

There will no longer, she said, be exclusions because a hospital deems treatment to be "low priority" or too specialised.

But there will still be people who can't be treated for a variety of reasons - what happens to them?

Under the new system, where patients become unavailable for treatment, they will not use their waiting time guarantee completely.

Instead, these periods will be taken into account when calculating the total waiting time.

How will that ensure patients do not continue to get lost in the system?

Ministers have likened the new regime to a clock. It starts when a GP referral is received by a hospital or when a decision is made to provide treatment.

The patient must be seen or treated before the clock shows the maximum waiting time.

If the patient is unavailable, the clock will stop and be re-started when their unavailability ends.

Patients whose clocks have been stopped will be kept under review and assurances given to ensure they do not remain so for any longer than necessary.

But surely there will continue to be patients who cannot be treated for an indefinite period of time?

There will, and in these circumstances, hospitals can remove them from a waiting list and refer them back to the care of their GP.

What if patients cannot make their appointments for other reasons?

Patients will be allowed to postpone and rearrange an appointment or admission twice. In these cases the waiting time clock will be reset to zero from the date of cancellation.

The hospital will then offer at least two further appointment dates with at least 21 days notice, within the maximum waiting time period.

So the system aims to be fairly flexible then?

Yes, but Ms Sturgeon has warned patients that they must treat the NHS with respect - people failing to attend appointments without good reason could expect to be removed from the waiting list and referred back to their general practitioner.

How will we know if the SNP government has made good on its promises?

Ms Sturgeon said the new system will be fully open to public scrutiny.