I don't consider my self either stupid or uneducated but I didn't understand a word of that thread.
I'll have a shot at explaining the different terms but I'm afraid it does get fairly complicated.
The stated annual management charge (AMC) for a fund is simply the fee paid to the fund manager, out of the fund assets, on an annual basis (normally expressed as a percentage of a fund's net asset value per unit). However, a fund will bear all sorts of other operating and trading costs that are not reflected in the AMC.
The Total Expense Ratio (TER) of a fund is equal to the ratio of the fund's total operating costs to the average net asset value of the fund during the preceding financial year. So, a fund's TER incorporates its AMC but also includes other operating costs (legal, audit, custody, etc.).
However, notwithstanding the name, a fund's TER does
not reflect the full ownership costs of holding a fund. In particular, it does not capture portfolio trading costs (currency conversion costs, brokerage costs, stamp duty, etc.).
To all intents and purposes, a fund's Ongoing Charges Figure (OCF) is essentially the new name for its TER (there are some technical differences but these are unimportant for these purposes). If you look at the Key Investor Information Document (KIID) for any UCITS fund, it will give you the fund's OCF.
So far so good?
The new EU regulations discussed on the earlier thread require a Key Information Document (KID) to be made available to investors in packaged retail and insurance-based investment products (PRIIPs). Importantly, certain pension products are exempted from the requirement (as are UCITS funds until 2019).
The PRIIPs KID is similar in many respect to a UCITS KIID but there are important differences. In particular, the impact of investment costs on an investor's projected return is expressed as a projected reduction in yield (RIY) figure (as opposed to the OCF discussed above, which is based on historic operating costs/NAV and excludes trading costs).
The methodology for calculating the projected RIY is relatively complex but, importantly, the figure aims to give potential investors a true and fair view of the projected impact on the projected returns of a fund of anticipated (a) operating costs; (b) distribution costs; and (c) portfolio trading costs.
Hopefully that helps.