2. Basics

Table 2.1 Definition of terms

Term	meaning
Sector	Basic unit of data handled by a CD block. (2352 bytes fixed) The sector size and structure follows the CD-ROM format.
stream	A logically continuous stream of data, distinguished by the sector header and subheader.
CD buffer	Buffer in the CD block that stores sector data.
CD buffer size	Size of CD buffer in sector units.
buffer partition	CD buffer divided into multiple logical partitions. It can be regarded as a logical element that stores and retrieves streams.
Buffer partition size	Size of the buffer partition in sectors.
Sector position	Sector position within the buffer partition. (Sector unit position) Takes values ​​from 0 to (buffer partition size -1). The sector of the buffer partition is accessed using the sector position as a key.
Aperture	A logical element that separates streams according to set conditions.
Selector	A logical element that consists of an aperture and a buffer section and selects a stream. A stream selection circuit can be constructed with a selector.
Device	A logical device that generates and absorbs streams, such as CD-ROM and MPEG. Stream selection processing is possible by connecting a device to the above circuit .
Connector	Terminal for connecting the aperture, buffer compartment, and device.
Frame address (FAD)	Continuous in frame units, with absolute time 00:00:00 on CD as 0 Numbered with. Corresponds to absolute time one-on-one. The CD block is accessed using the frame address as a key, not the absolute time. (Both CD-ROM and CD-DA)
Logical sector number (LSN)	Sector (frame) with absolute time 00:02:00 on CD as 0 with consecutive numbers in units. Logical sector number = Frame address-150 (2 seconds). Used for information in directory records (ISO9660).
File information	Directory record information held for accessing files. There are FAD, file size, unit size, gap size, file number and attributes at the beginning of the file.
File identifier	Order number in the directory to identify the file. Takes values ​​from 0 to (number of directory records minus 1) However, 0: My directory, 1: Parent directory.