> For the complete documentation index, see [llms.txt](https://initiativ.gitbook.io/initiativ/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://initiativ.gitbook.io/initiativ/mm_internal/4.-trading-mechanisms/4.6-instruments-and-trading-mechanisms.md).

# 4.6 Instruments and trading mechanisms

This table ties Chapters 3 and 4 together: it maps each instrument listed at launch (Chapter 3) to the mechanisms through which it can be traded (this chapter). It sits here, at the close of Chapter 4, because it only fully makes sense once the mechanisms have been introduced.

| Instrument                               | Code                  | On-screen continuous \[a] | RFQ                          | Trade Scheduler | Block Clear \[c] |
| ---------------------------------------- | --------------------- | ------------------------- | ---------------------------- | --------------- | ---------------- |
| EUA spot                                 | EA1S                  | Yes                       | —                            | Yes (TAS) \[b]  | Yes              |
| EUA standard (monthly) future            | EA1F + month + year   | Yes                       | Yes (block; TAS) \[b]        | —               | Yes              |
| EUA weekly future                        | EA1W + DDMMMYY        | Yes                       | Yes (block; TAS) \[b]        | —               | Yes              |
| EUA futures calendar spread              | EA1F + two maturities | Yes (implied)             | Yes (block, 25 lots per leg) | —               | Yes              |
| Physical-versus-future basis spread \[d] | EA1S + future leg     | Yes (implied)             | Yes (larger size)            | —               | Yes              |

\[a] On-screen continuous. For outright instruments this is the central order book under strict price-time priority (Section 4.1). For spreads it is the implied-priced spread book, a pricing and display layer over the two underlying leg books with atomic two-leg execution, implied-in only at launch; there is no separate matched book (Sections 3.1.4, 4.1).

\[b] TAS and TAA are Marker trades, defined in Section 4.5. TAS on spot routes to the Trade Scheduler (Section 4.4); TAS on futures is offered through RFQ (Section 4.2), across maturities where the minimum liquidity condition is met. TAA would likewise route through RFQ and is not confirmed at launch.

\[c] Block Clear carries pre-negotiated bilateral trades that meet the block minimum: 50 lots for EUA futures, 50,000 allowances for EUA spot, and 25 lots per leg for calendar spreads (Sections 4.2, 4.3).

\[d] The physical-versus-future basis spread is a launch aim, conditional on the central counterparty accepting and margining a mixed-leg product. If that treatment is not ready at launch, the basis trades through standard routes (future-versus-future spreads, EFP and repo) and the on-screen spread follows once the CCP underwrites it (Section 3.1.4).

The daily future (T+1) is not a launch product; it is retained only as a fallback should the basis spread prove unclearable (Section 3.1.3).