## Average

**is an abstract direct subtype of Type with functions Quotable Functions, direct subtypes Quotable subtypes and keys Quotable keys that represents the parent Deriscope Type of any Deriscope Object that describes a financial variable.**

*Quotable*Any Quotable can be in principle evaluated at any time provided sufficient market and model information is available.

All Quotable objects contain the function Value.

Inversely if a type contains the function

**then it must be a subtype of Quotable.**

*Value*Examples of quotables (i.e. types deriving from Quotable) are: Stock Price, Ibor Rate, Discount Factor Group etc.

Note that just as a Tradable is "pricable" but itself does not contain the associated "price", similarly a Quotable is "valuable" but itself does not contain the associated "value". The "value" is calculated at run time by means of the function

**.**

*Value*For example a Ibor Rate object does not contain the actual "rate value" (e.g. 4%).

It only contains the structural definitions such as Maturity, Frequency, Currency, Daycounts etc.

The "value" (i.e. the associated deposit rate number) can be calculated at run time, if sufficient discount factor data and modeling assumptions are provided.

Interestingly the "value" that can be assigned to a particular Quotable may not be just a single number.

A Quotable such as Ibor Rate expects a single number (such as .04) as "value".

On the other hand the Quotable type Discount Factor Group expects a whole curve (which is mathematically equivalent to an infinite dimensional vector) as associated "value".

Often when the observation date lies in the future, the associated "value" is a whole probability distribution (referred as Probability Measure in Deriscope).