There is no limit to the level of nesting which you can use in a query. Structured or Boolean queries must follow specific syntax rules as noted below, including proper use of special operators, use of parentheses, and bounded phrases in quotes.
Different treatment applies to natural queries vs. Boolean queries.
Natural or simple text queries can have a series of keywords entered separated by spaces or commas. If commas are used, they are ignored. Structured queries behave exactly as you have specified them, assuming proper Boolean syntax. When using a structured Boolean query, you may on occasion notice many more results than what the query itself would normally suggest. In these cases of no matched results, CompletePlanet defaults to a 'relaxed' site search mode where all query terms are treated like a natural language or simple text search.