One of the reasons an exchange will not send fees with the order is if they do discounts for order volume. If you trade over X shares a month or within a day, then your fee rate is different and the one sent to you with your orders would not be correct at the end of the day.
fair enough - I haven't (yet) traded in that kind of volume. Even if it's the max fee, then that is "good enough" as then I'll make more profit.
The actual order confirmation should contain the real fee which should never be more than this max.
Another reason is if their reconciliation systems are different from the matching engine. This is true at bitfloor. Our matching engine does not care what user you are and thus does not have your details (like fee structure). If we were to have different fees for different users then it would not know what fee to apply (since again it does not deal with user data).
I guess it would also get messed up by intersango's new fee structure of different fees for immediate matching as against speculative.
I also like the idea of having a machine readable fee schedule (but again would need to consider the case where it might be per user, which it is not currently). If anything, users should be able to at least get daily, weekly, or monthly trade reports summarizing their activity.
I think having a dynamic user fee schedule would be great, however I'm fairly realistic in only wanting a defined sitewide fee structure to be updated as the max fee that a trade would be, I can't imagine that it would change that frequently, but also advantages such as CryptoXchange's 0% fee this week would be immediately notified. It's helpful in making a decision, a lower tx fee at a different volume would be no different than a buy/sell order at partially filled at two different rates. In the end the executed order should have the information for the bot/spreadsheet to update.
Also I think I missed out on defining which side the fee would be. (is a usd->btc trade fee in usd or btc.)
I'm gradually working my way through the exchanges to see what functionality they have in each, which are unique and common. Bitfloor is on my list but I probably won't get to it until next week.
I'm probably being a bit pedantic about this because I'm currently building a spreadsheet in which I know I'll make mistakes that are trivially avoidable (so far I've put in 6.5 and 0.065 for the fees in trading calculations.)
how does the large commerical financial exchanges handle this?