Similar to other essential oils, rosemary fragrance oil is often a single-note or straightforward representation of the rosemary scent. In the context of traditional top, middle, and base notes, which are more applicable to complex perfumes with multiple ingredients, you can still describe the fragrance in a simplified manner:

Top Note: The initial burst of the fragrance, capturing the immediate and sharp freshness of rosemary. This may include the herbaceous, woody, and slightly camphoraceous qualities that are noticeable right away.

Middle Note: The body of the fragrance, representing the sustained herbaceous and woody aspects of rosemary. This note contributes to the overall perception of the fragrance as you continue to experience it.

Base Note: Rosemary oil doesn't typically have a strong base note in the traditional sense, as its fragrance tends to be more straightforward and doesn't undergo significant changes over time. However, the lasting impression could be described as a milder version of the initial herbaceous and woody qualities.

Rosemary fragrance is often used for its aromatic and herbaceous qualities, and it is associated with a fresh and uplifting scent. Keep in mind that the concept of top, middle, and base notes is more applicable to complex perfumes, and single-note fragrances like rosemary may not follow this structure as closely.