parameter of ko.observable constructor Options Hash: (option): key (String) — the name of the attribute. read (Function) — a function used to provide transform the attribute value before passing it to the caller. Signature: read() write (Function) — a function used to provide transform the value before passing it to the model set function. Signature: write(value) args (Array) — arguments to pass to the read and write functions (they can be ko.observables). Can be useful for passing arguments to a locale manager. localizer (Constructor) — a concrete kb.LocalizedObservable constructor for localization. default (Data|ko.observable) — the default value. Can be a value, string or ko.observable. path (String) — the path to the value (used to create related observables from the factory). store (kb.Store) — a store used to cache and share view models. factory (kb.Factory) — a factory used to create view models. options (Object) — a set of options merge into these options using _.defaults. Useful for extending options when deriving classes rather than merging them by hand.