After defeating the government on Monday night, lawmakers are holding a series of "indicative" votes, in an attempt to find a Brexit plan that commands majority support in Parliament.

We don't yet know exactly what alternatives will be selected for debate, but these are the main Brexit options.

Theresa May's deal

Theresa May's deal -- otherwise known as the Withdrawal Agreement -- was agreed with the EU last November. Its aim, broadly, was to allow the UK to formally leave on a set date (originally March 29), while abiding by EU rules for a further 21-month "implementation period".

This gives the UK and EU breathing space while they hammer out the details of a future relationship.

Brexiteers hate this because it means following the rules of the EU's Customs Union and Single Market while having no say in either -- which hardly accords with their mantra of taking back control.

The Withdrawal Agreement also contains the controversial Northern Ireland backstop. In essence, this is an emergency cord to be pulled if no way has been found to prevent a need for infrastructure on the Northern Irish border after the implementation period ends. Why is this so controversial?

Because the backstop would place the entire UK inside a single customs territory with the EU. That probably means no independent trade policy, the holy grail for leave campaigners.

If lawmakers agree May's deal, it would mean the UK leaving the EU on May 22 and entering the implementation period. But if May can't pass her deal, then another way forward needs to be found.

So what are these other options likely to be?

Norway Plus, or Common Market 2.0

Norway Plus -- or Common Market 2.0 , as some are now calling it -- is a very soft Brexit, in which the UK formally leaves the EU but remains very closely aligned to it. The "plus" part of this plan would be a customs arrangement between the UK and the EU that avoids a hard border on the island of Ireland.

Norway Plus has advantages and disadvantages, dependent on your perspective.

Under this plan, the UK would apply to join the European Free Trade Association, which would allow the UK to trade with the EU and other EFTA nations (Iceland, Liechtenstein, Norway and Switzerland) on similar terms to now.

Via EFTA, the UK would also continue its membership of the European Economic Area, meaning it would retain access to the EU's single market.

Under EFTA rules, the UK can still -- in theory at least -- strike its own trade deals while more or less maintaining trading ties with the EU. It will also result in minimal disruption to its world-class services industry.

The UK would also leave the jurisdiction of the European Court of Justice in all areas other than those which affect the EEA. Crucially for some Brexiteers, the UK could also leave the EU's Common Agricultural Policy and Common Fisheries Policy. (Despite making up less than 0.05% of the UK's economy, the fishing industry has played a huge part of the Brexit debate.)

But as a member of the single market, the UK would have to abide by the four freedoms of movement: Goods, services, capital and people. That last one is a problem for Brexiteers, as it means the UK would not have full control over the number of people coming through its borders.

The UK would have to continue making huge contributions to the EU, something that Brexiteers promised would end.

And the unique customs arrangement envisioned by Norway Plus is unprecedented among EFTA membership, so there's no guarantee that it could be achieved, meaning the Irish border question is not necessarily answered. So, while it looks a very clever plan, Norway Plus runs into many of the same problems as every other plan.

Permanent customs union

The main opposition Labour Party has faced wide criticism for not presenting a coherent Brexit plan. One thing we do know, however, is that it favors a permanent customs union with the EU, in which the UK has a say in future trade deals.

A customs union is essentially a free-trade agreement between a number of countries who agree to share common external tariffs. That means no customs checks at borders. But because the EU is one large trading bloc, it also has a unified external trading policy, which EU member states can influence, but is ultimately run out of Brussels.

First, it should be noted that Labour favors "a" customs union, not "the" Customs Union. But in reality, this differs very little from May's "backstop" plan of a single customs territory. Moreover there is no clear mechanism in which the UK could have a say in future EU trade deals.

The other elements of the Labour Plan are maintaining a "strong relationship" with the single market and retaining EU standards on workers' rights.

Those are the three plans that have the support, respectively, of the government, the opposition, and the group of MPs that took control of the Brexit process earlier this week. Or in other words, the three main ones to look out for. But there are other options that the Commons will likely consider.

No deal

Brexit may not mean Brexit, but no deal really does mean no deal. The UK would leave the EU on April 12 and become a third-party nation. It would trade with the world on terms set by the World Trade Organization and would fall out of all EU institutions. This would affect everything from medical supplies to air travel.

For those agitating for a softer Brexit, and for the government, it is tactically sensible to allow the Commons to have a final say on a no-deal Brexit.

For the softer Brexit types, it means they can rule out what they see as the worst-case scenario once and for all. For the government, it gives May the chance to prove to her hardliners that they are a minority in parliament and if they want to see Brexit delivered, it's her deal or something much worse.

Canada-style free trade agreement

Canada and the EU endured excruciating negotiations over seven years before they agreed on the Comprehensive Economic and Trade Agreement (CETA).

CETA eliminates 98% of tariffs between Europe and Canada on certain goods and offers has access to much of the EU services market. The agreement is essentially a looser trading arrangement which removes many barriers between Europe and Canada. However, because Canada is not a member of the Customs Union or Single Market, customs checks still exist.

For reasons discussed earlier, this doesn't satisfy the Irish border question. The harder Brexiteers who want a looser relationship with Europe favor this plan, claiming that solutions will inevitably be found to deal with the border. But they have yet to produce any concrete solutions themselves.

Revoke Article 50

At the time of writing, it's unclear if the option of a holding second referendum will be discussed on Wednesday. Supporters of another public vote say that it's not a Brexit outcome, but a matter of process, and should be debated separately on its own merit.

However, in the eyes of many, a second referendum is the only way the UK could credibly revoke Article 50, the process of leaving the EU, and remain in the bloc on its current terms.

A big show of support for revoking Article 50 would be helpful for advocates of a second referendum. Whether they will get it or not is another issue entirely.