The phrase "allows the addition of" is correct and usable in written English.
It can be used when describing a feature or capability that enables something to be added or included.
Example: "The software allows the addition of new user accounts to the system."
Alternatives: "permits the inclusion of" or "facilitates the addition of".
Embossing allows the addition of a second colour into the resultant depressions, producing an inlaid effect.
This allows the addition of further annotations and metadata either directly on the descriptor node or on its class node.
The modularity and extensibility of the platform allows the addition of new technologies, different data fusion approaches, etc.
The design of both the academic portal and the mobile application allows the addition of new languages for the resources.
The Springboard slot in the Handspring Visor even allows the addition of keyboards, MP3 players or a device that reads news articles aloud.
Expansion: in a sequent calculus where weakening is absent, expansion allows the addition of another occurrence of a formula whenever there is already one in a sequent.
In addition, the system permits additional discretionary information in the form of comment boxes which allow the addition of clinical comments (see also Figure 1).
The QNX operating system should allow the BlackBerry to shed its reputation for sluggish operation and allow the addition of several new features.
The Duke plant is engineered to allow the addition of equipment to capture much of the carbon dioxide from the fuel gas.
Cleverer still, Code On's approach recombines elements of formulae from multiple packets into each chunk sent, allowing the addition of redundancy.
After three years there, it moved to the hunt club, a larger facility that allowed the addition of more show cars and related exhibits.
