[GNC] Importing stock prices from a CSV file

[flywire]

While importing csv files is only really explained in the manual
https://www.gnucash.org/docs/v5/C/gnucash-manual/trans-import.html#trans-import-csv
(not the guide) in terms of transactions, there is a lot of supporting
information for the Price Import Assistant in
https://www.gnucash.org/docs/v5/C/gnucash-manual/tool-price.html and
https://www.gnucash.org/docs/v5/C/gnucash-manual/tool-security-edit.html

The term security seems to be used interchangeably (ie it's not a subset)
with commodity and a symbol is a property of a commodity.

   -

   *Commodity: *A commodity is something of value that is easily tradeable
   or sellable; for example, currencies, stocks, bonds, grain, copper, and oil
   are all commodities.

https://www.gnucash.org/docs/v5/C/gnucash-manual/tool-security-edit.html
clearly describes Securities types are currency, fund, listing stock
exchange, or a user defined type. It seems some user defined types, for
example grain, would turn this into a commodity. It conflicts with the
second sentence below:

   -


*Security: The Security/commodity being priced. The display is sorted by
   the Namespace that the individual securities are listed on. *
   -

   *Symbol:* Indicates the symbol or abbreviation for the commodity. This
   is usually the ticker symbol (for stocks) or other unique abbreviation for
   the commodity. If the commodity is traded on any public exchange, it is
   important to use the same identifier used on that exchange. For national
   currencies the symbol is the ISO-4217 currency code.
   -

   *Namespace:* What is a reasonable description of this group [of
   commodities ??] ?  The only reference to Namespace in the documentation is
   quoted above but referring to a group of stock by listing exchange is too
   restrictive.