A couple of the Isearch+ features that let you limit the search space/context.

1. You can limit isearching to the text in the region. Controlled by a user option, and can be toggled with C-x n during Isearch. Works also for a noncontiguous region, such as a rectangle.

2. You can switch any time to isearching outside, instead of inside, the region.

3. You can search within/without the zones of text defined by the lazy-highlight matches of a previous search.

Or search within/without the zones of text that have a certain text property or set of properties (optionally considering their values) – any properties.

4. Dynamic Isearch filtering: add/remove any number of search filters while isearching.

• Isearch+

• Dynamic Isearch Filtering