When an index is created, an empty set of files is built in the folder specified for the index. The index's alphabet and noise word list are initialized and cannot be changed without deleting the index. The alphabet file is copied into the index as index_a.ix, and the noise word list is copied into the index as index_n.ix. 

Several properties of an index are also established when the index is created: 

(1) Relative paths, which cause the index to store relative rather than absolute paths to documents in an index. 

(2) Case sensitivity, which determines whether the index considers words that are capitalized differently to be different words. 

(3) Accent sensitivity, which determines whether accents in letters are considered significant when searching. 

(4) Caching of text in the index

Building and Maintaining Indexes