(12)The primary rules with respect to participation, exposure management, margin requirements, default funds, other financial resources, default waterfall and default procedures, follow a similar approach to the rules contained in Title IV of Regulation (EU) No 648/2012 but differ in some aspects. With respect to the initial margin applied to clearing member's proprietary positions the primary rules provide for a minimum liquidation period of one day for non-OTC derivative contracts including futures, options, swaps on agricultural energy commodities and metals and five days for all other derivatives, with margin collected on a net basis. Union rules, however, set out minimum liquidation periods of two days for non-OTC derivative contracts and five days for OTC derivative contracts, typically with margin collected on a net basis. With respect to clearing members' proprietary positions therefore, the higher liquidation period of two days for non-OTC derivative contracts in the Union results in CCPs authorised in the Union collecting more margin in respect of those positions. Conversely, in the case of initial margins collected with respect to the positions of clients of clearing members, the primary rules require margin to be collected on a gross basis for all classes of derivative contracts, whereas Union law has no such requirement. This difference between net and gross margin collection results in equivalent outcomes with respect to the amount of margin that DCOs hold with respect to the positions of clients, which compensates for the difference in the liquidation period. Therefore the primary rules on margin requirements can be considered equivalent to Union law in so far as they relate to the positions of clients of clearing members. Further, Union law requires the application of one of three anti-procyclicality measures to ensure that initial margins do not fall too low in stable economic times and do not increase precipitously in times of stress, whereas the primary rules contain no such specific requirement. In doing so, such measures deliver stable and conservative margins. Additionally, the primary rules require SIDCOs and opt-in DCOs to apply the ‘cover 2 principle’ where those DCOs have been designated as being systemically important in multiple jurisdictions or where they are involved in activities with a more complex risk profile. Union rules, in contrast, require the ‘cover 2 principle’ for all CCPs.