Interesting bit from the Barclays ATS – LX and Equities Electronic Order Handling FAQ:

Opt-out notice: By default, all firm orders sent by Barclays algorithms will be conditional-eligible so that clients’ orders may interact with the maximum amount of potential liquidity. If you have any questions regarding how conditional orders operate, or if you do not want your algorithmic orders to be conditionally eligible, you can opt out of this functionality by contacting your Barclays Equities sales representative

If you don't opt out, they'll sorta kinda protect your interests:

Barclays may revoke or limit a participant’s ability to submit conditional negotiations if the subscriber exhibits a low rate of responding to conditional invitations with firm-up orders. ... Firm-up rates are monitored across all conditional-supported venues, including Barclays LX.

UBS "expects" traders using their ATS will come through with a firm-up order. But no word from them on monitoring firm-up rates.