Catalunya's independentistas would like this month's regional elections to be seen as a straight Yes or No on sovereignty, a referendum in all but name. Their opponents, however, see the vote in a very different way. That's because Catalunya's three-dimensional politics has only partly recalibrated across what Scots might call a nationalist-unionist spectrum.

The elections are scheduled for September 27 - or "27S" - and polls suggest a tight victory for pro-independence groups. But who exactly is running, what do they stand for and what are the big trends to look out for? Here is The Herald's at-a-glance guide to all seven slates in the Catalan elections:

Junts pel Sí.

Indy? Pro

Left or right? Left to Centre

This single slate, forged this summer from left and centrist parties and a variety of public figures, believes next week's parliamentary elections will be a platform for independence, even without a Scottish-style referendum.

The group, called JxS for short or Together for Yes in English, includes both Catalunya's current ruling centrists, Convergència Democràtica de Catalunya, and their one-time opponents Esquerra Republicana, the Republican Left, formal allies of the SNP.

What to watch for: Can JxS together with their leftist pro-indy allies CUP win either an absolute majority of seats, or a majority of votes?

Popular Unity Candidacy or CUP

Indy? Pro

Left or right? Radical left.

Although not part of the JxS slate, CUP's votes and seats will effectively been seen as an endorsement for independence. The party, however, aims for a broad left participative democracy throughout Catalan lands, including in parts of Spain not formally considered to be part of Catalunya in its current borders.

What to watch for: can CUP help JxS cross win enough seats and votes to win legitimacy for a parliamentary route to independence?

Catalan Socialist Party or PSC

Indy? Anti

Left or right? Centre left

This is the autonomous Catalan wing of Spain's main centre left socialist party, PSOE. It favours a federal Spain but struggles to find much support for this position outside Catalunya. Until a decade ago, PSC collected nearly a third of Catalan votes in "regional elections" and has only once, in 2011, failed to win the Catalan segment of "national" elections to the Spanish parliament.

What do watch for: Just how low can the equivalent of Scottish Labour fall?

Ciutadans or Citizens.

Indy? Anti.

Left or right? Centre left.

This "anti-nationalist" group, born in Catalonia, has now grown to become a force across the Spain. Sometimes referred to by its Spanish name, Ciudadanos.

What to watch out for: just how much damage this still relatively new party can do to the PSC? And will Ciutadans emerge, as some polls suggest, as the second force in Catalan politics?

Popular Party or PPC

Indy? Anti

Left or right? Right.

This is the Catalan wing of Spain's ruling Partido Popular or Conservatives. It remains deeply opposed to both independence and a vote on independence.

What to watch for: Can Spain's ruling party garner a tenth of the Catalan vote? Has a hard line on indy toughened up support for Spain's "Populares" in Catalunya?

Catalunya Sí que es Pot

Indy? Ambivalent

Left or right? Radical left and Green

This is a single slate - its name, roughly translated, means "Catalunya, Yes We Can" - representing four parties or movements: Greens, Eco-socialists, former Communists and the Spanish-wide Podemos anti-establishment left group.

The loose grouping broadly opposes full statehood and rejects JxS's parliamentary route to independence but supports the right of the Catalan people to decide their future in a referendum.

What do watch for: Have the wheels come off the anti-establishment bandwagon of Podemos in Catalunya as polls in Spain show some switch back to mainstream parties? Will planned last-minute speeches by Podemos leader Pablo Iglesias resurrect their campaign?

Unió Democràtica de Catalunya

Indy? Anti

Left or right? Right

Until recently, this Catalanist "home rule" party governed Catalunya with the liberal Convergència but split from long-term partners over independence.

What to watch for: Will Unió - and traditional right-wing regionalism - be adrift with just two or three deputies after next week?