1. An authoring tool, embedded in a non-transitory tangible computer readable medium, the authoring tool configured to: enable authoring of a gallery card among a plurality of cards of a wrap package, the gallery card having a fixed layout of content authored into the card, the authoring tool enabling an author to: (a) select a gallery card for authoring; (b) select a gallery item template; (c) author content into a new gallery item derived from the selected gallery item template; (d) author a plurality of gallery items for the gallery card by authoring content into each of a plurality of gallery items respectively; and (e) define a sequence order for rendering the plurality of gallery items of the gallery card; the authoring tool further including a behavior tool for declaring a transitional behavior that is associated with the plurality of gallery items when the gallery card is navigated; the authoring tool further configured to: (1) generate a plurality of gallery item descriptors for the plurality of gallery items respectively, each of the gallery item descriptors defining a fixed aspect ratio and a fixed layout for the content authored into the associated gallery item respectively; (2) generate a JSON gallery card descriptor including the plurality of gallery item descriptors; and (3) generate a JSON wrap descriptor that represents the wrap package of cards, the wrap descriptor including a plurality of card descriptors for the plurality of cards of the wrap package including the JSON gallery card descriptor for the gallery card, wherein the gallery card has a fixed presentation that is defined by: (i) the defined sequence order for rendering the plurality of gallery items; (ii) the fixed layout of the content authored into each of the plurality of gallery items respectively; and (iii) the fixed aspect ratio of the gallery card, wherein the fixed presentation of the gallery card is maintained as authored when the wrap package is rendered on a consuming device regardless of the type or class of the consuming device or the size or orientation of the rendering environment provided by the consuming device, wherein the gallery card is imbued with a behavior corresponding to the declared transitional behavior by a runtime viewer located at the consuming device when the wrap package is rendered, wherein the behavior is selected from a library of behavior definitions maintained by the runtime viewer.
1. An authoring tool, embedded in a non-transitory tangible computer readable medium, the authoring tool configured to: enable authoring of a gallery card among a plurality of cards of a wrap package, the gallery card having a fixed layout of content authored into the card, the authoring tool enabling an author to: (a) select a gallery card for authoring; (b) select a gallery item template; (c) author content into a new gallery item derived from the selected gallery item template; (d) author a plurality of gallery items for the gallery card by authoring content into each of a plurality of gallery items respectively; and (e) define a sequence order for rendering the plurality of gallery items of the gallery card; the authoring tool further including a behavior tool for declaring a transitional behavior that is associated with the plurality of gallery items when the gallery card is navigated; the authoring tool further configured to: (1) generate a plurality of gallery item descriptors for the plurality of gallery items respectively, each of the gallery item descriptors defining a fixed aspect ratio and a fixed layout for the content authored into the associated gallery item respectively; (2) generate a JSON gallery card descriptor including the plurality of gallery item descriptors; and (3) generate a JSON wrap descriptor that represents the wrap package of cards, the wrap descriptor including a plurality of card descriptors for the plurality of cards of the wrap package including the JSON gallery card descriptor for the gallery card, wherein the gallery card has a fixed presentation that is defined by: (i) the defined sequence order for rendering the plurality of gallery items; (ii) the fixed layout of the content authored into each of the plurality of gallery items respectively; and (iii) the fixed aspect ratio of the gallery card, wherein the fixed presentation of the gallery card is maintained as authored when the wrap package is rendered on a consuming device regardless of the type or class of the consuming device or the size or orientation of the rendering environment provided by the consuming device, wherein the gallery card is imbued with a behavior corresponding to the declared transitional behavior by a runtime viewer located at the consuming device when the wrap package is rendered, wherein the behavior is selected from a library of behavior definitions maintained by the runtime viewer. 19. The authoring tool of claim 1 , wherein the fixed presentation of the set of cards of the wrap package, including the gallery card, remains the same in different rendering environments associated with different types or classes of consuming devices, including but not limited to mobile phones, tablet computers, laptop computers, desktop computers, smart TVs respectively.