What must be true for a parcel to be classified as an outside parcel?

For a parcel to be classified as an outside parcel, it is essential that it cannot be processed in postal sacks due to its size or shape. This classification is typically used for items that exceed the standard dimensions for parcels that can be bundled together for easier handling and transportation. Such items are often too large, bulky, or oddly shaped to fit into the standard postal processing equipment, which requires that they be treated as separate from regular parcels that can be accommodated in sacks.

The focus on size and shape is crucial here because it dictates how the item can be handled throughout the postal system. Items classified as outside parcels require special attention because traditional processing methods may not apply, impacting how they are packaged and shipped.

The other options relate to specific characteristics that do not fundamentally determine the classification of a parcel as outside. For example, weight alone does not classify a parcel as outside; various items under that weight can still be within the standard processing categories. Similarly, the need to be sent internationally, or being sealed with tape, does not inherently connect to external classification; domestic parcels might also fall under the same rules if they are oversize. Thus, the criteria focus on the processing capabilities of the postal system concerning the parcel's dimensions.