here - OSTA - Optical Storage Technology Association
here - OSTA - Optical Storage Technology Association
here - OSTA - Optical Storage Technology Association
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2. Basic Restrictions & Requirements<br />
The following table summarizes several of the basic restrictions and requirements defined<br />
in this specification. These restrictions & requirements as well as additional ones are<br />
described in detail in the following sections of this specification.<br />
Item<br />
Logical Sector Size<br />
Logical Block Size<br />
Volume Sets<br />
First 32K of Volume Space<br />
Volume Recognition Sequence<br />
Timestamp<br />
Entity Identifiers<br />
Descriptor CRCs<br />
File Name Length<br />
Extent Length<br />
Primary Volume Descriptor<br />
Anchor Volume Descriptor Pointer<br />
Partition Descriptor<br />
Restrictions & Requirements<br />
The Logical Sector Size for a specific volume shall be the<br />
same as the physical sector size of the specific volume.<br />
The Logical Block Size for a Logical Volume shall be set to<br />
the logical sector size of the volume or volume set on which<br />
the specific logical volume resides.<br />
All media within the same Volume Set shall have the same<br />
physical sector size. Rewritable/Overwritable media and<br />
WORM media shall not be mixed in/ be present in the same<br />
volume set.<br />
The first 32768 bytes of the Volume space shall not be used<br />
for the recording of ECMA 167 structures. This area shall<br />
not be referenced by the Unallocated Space Descriptor or<br />
any other ECMA 167 descriptor. This is intended for use by<br />
the native operating system.<br />
The Volume Recognition Sequence as described in part 2 of<br />
ECMA 167 shall be recorded.<br />
All timestamps shall be recorded in local time. Time zones<br />
shall be recorded on operating systems that support the<br />
concept of a time zone.<br />
Entity Identifiers shall be recorded in accordance with this<br />
document. Unless otherwise specified in this specification<br />
the Entity Identifiers shall contain a value that uniquely<br />
identifies the implementation.<br />
CRCs shall be supported and calculated for all Descriptors,<br />
except for the Space Bitmap Descriptor. T<strong>here</strong> is a CRC<br />
length special case for the Allocation Extent Descriptor.<br />
Maximum of 255 bytes<br />
Maximum Extent Length shall be 2 30 – 1 rounded down to<br />
the nearest integral multiple of the Logical Block Size.<br />
Maximum Extent Length for extents in virtual space shall be<br />
the Logical Block Size.<br />
T<strong>here</strong> shall be exactly one prevailing Primary Volume<br />
Descriptor recorded per volume. The media w<strong>here</strong> the<br />
VolumeSequenceNumber of this descriptor is equal to 1<br />
(one) must be part of the logical volume defined by the<br />
prevailing Logical Volume Descriptor.<br />
Shall be recorded in at least 2 of the following 3 locations:<br />
256, N-256, or N, w<strong>here</strong> N is the last addressable sector of a<br />
volume. See also 2.2.3.<br />
A Partition Descriptor Access Type of Read-Only,<br />
Rewritable, Overwritable and WORMWrite-Once shall be<br />
supported.<br />
T<strong>here</strong> shall be exactly one prevailing Partition Descriptor<br />
recorded per volume, with one exception. For Volume Sets<br />
that consist of single volume, the volume may contain 2<br />
UDF 2.01<br />
8<br />
March50 April