SEC-113 - Missing Security Restriction(s) related to short selling

[ElisaKendall]

In https://dil-edmcouncil.atlassian.net/browse/SEC-113, in the Securities Restrictions ontology we are missing restrictions that arise around short selling (as a kind of trading restriction) some of which are mandated by regulation (e.g. Regulation SHO) and others possibly by a given exchange. This issue was originally raised in the context of SEC-96, but belongs as its own issue against the securities restriction ontology.

These include:

1. EU Short Selling Eligibility Flag - This field indicates whether the security has been marked restricted for short selling by the EU Short Sell Regulation.
2. Security Short Sale Flag - This field indicates whether the short sale circuit breaker is in effect. The Securities and Exchange Commission (SEC) short sale alternative uptick rule (Rule 201) requires the establishment of a short sale-related circuit breaker in the event a security's price decreases by ten percent or more from the previous day's closing price. Once activated, the short sale restriction will remain in effect for the remainder of the day as well as the following day. Values are A - "Flag in Effect/Activated", C - "Flag Continued" and N - "Flag Not in Effect". If not given the default is "N - Flag Not in Effect".

See also https://dil-edmcouncil.atlassian.net/browse/SEC-97.