How does the transitional phrase “composed of” compare to “consisting of” in patent claims?

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Source: FAQ (MPEP-Based) BlueIron Update: 2024-09-29 10 Rules 5 Related FAQs This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice. How does the transitional phrase “composed of” compare to “consisting of” in patent claims? The transitional phrase “composed of” is generally treated similarly to “consisting of” in patent claims, but with some nuances: Similar to “consisting of”: “Composed of” is typically interpreted as a closed transition, excluding unrecited elements. Potential flexibility: In some cases, “composed of” might be interpreted more flexibly than “consisting of,” depending on the context and specification. According to MPEP 2111.03 : “ The transitional phrase ‘composed of’ has been interpreted in the same manner as either ‘consisting of’ or ‘consisting essentially of,’ depending on the facts of the particular case. “ While “composed of” is generally treated as a closed transition like “consisting of,” its interpretation can depend on the specific circumstances of the case. Examiners and practitioners should carefully consider the context and specification when interpreting claims using “composed of” as a transitional phrase. Related Rules from the Manual of Patent Examining Procedure 10 rules Collapse Claims Using Consisting Of Are Closed To Unrecited Elements MPEP 2111.03 Transitional Phrase 'Composed Of' Is Interpreted Flexibly MPEP 2111.03 Scope Defined by Transitional Phrases MPEP 2111.03 Having Must Be Interpreted Based on Specification MPEP 2111.03 Required Consisting Essentially Of Is Equivalent To Comprising For Prior Art Search MPEP 2111.03 Consisting of Limits Only Recited Elements MPEP 2111.03 Consisting of Does Not Limit Entire Claim MPEP 2111.03 Interpretation of Composed Of MPEP 2111.03 Permitted Pending Claims Must Be Interpreted Broadly MPEP 2111 Required Claims Must Be Interpreted Broadly fo...