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209 lines
6.7 KiB
HTML
209 lines
6.7 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
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<html>
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<head>
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<title>DDL for HDF5</title>
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</head>
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<body>
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<h1>DDL in BNF for HDF5</h1>
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<h2>1. Introduction</h2>
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This document contains the data description language (DDL) for an HDF5 file.
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The description is in Backus-Naur Form.
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<h2>2. Explanation of Symbols</h2>
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This section contains a brief explanation of the symbols used in the DDL.
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<PRE>
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::= defined as
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<tname> a token with the name tname
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<a> | <b> one of <a> or <b>
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<a><FONT SIZE=1.7>opt</FONT> zero or one occurrence of <a>
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<a>* zero or more occurrence of <a>
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<a>+ one or more occurrence of <a>
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TBD To Be Decided
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</pre>
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<h2>3. The DDL</h2>
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<dir>
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<pre>
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<file> ::= HDF5 "<file_name>" { <file_boot_block><FONT SIZE=1.7>opt</FONT> <root_group> }
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<file_name> ::= <identifier>
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<file_boot_block> ::= BOOT_BLOCK { <boot_block_content> }
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<boot_block_content> ::= TBD
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<root_group> ::= GROUP "/" { <unamed_datatype>* <group_attribute>* <group_member>* }
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<unamed_datatype> ::= DATATYPE "<unamed_type_name>" { <compound_type_def>+ }
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<unamed_type_name> ::= the assigned name for unamed type is in the form of
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#oid1:oid2, where oid1 and oid2 are the object ids of the type
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<compound_type_def> ::= <named_scalar_type> | <named_array_type>
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<named_scalar_type> ::= <scalar_type> <field_name> ;
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<scalar_type> ::= H5T_STD_I8BE | H5T_STD_I8LE | ...
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<field_name> ::= <identifier>
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<named_array_type> ::= <scalar_type> <field_name> <dim_sizes> ;
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<dim_sizes> ::= dimension sizes in the form of [dimsize1][dimzise2]...,
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where dimsize1, dimsize2 are integers
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<group_attribute> ::= <attribute>
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<attribute> ::= ATTRIBUTE "<attr_name>" { <datatype>
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<dataspace>
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<data><FONT SIZE=1.7>opt</FONT> }
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// <datatype> and <dataspace> must appear before <data>.
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<attr_name> ::= <identifier>
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<datatype> ::= DATATYPE { <named_type> } |
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DATATYPE { "<scalar_type>" } |
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DATATYPE { <compound_type_def>+ }
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<named_type> ::= <hardlink>
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<hardlink> ::= HARDLINK { "<abs_name>" }
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<abs_name> ::= object absolute name
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<dataspace> ::= DATASPACE { "<dataspace_name>" } |
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DATASPACE { ARRAY <current_dims> <max_dims> } |
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DATASPACE { OTHER <ds_definition>+ }
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<dataspace_name> ::= <identifier>
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<current_dims> ::= a list of integers in the form of (<i>i<FONT SIZE=1.0>1</i></FONT>, <i>i<FONT SIZE=1.0>2</i></FONT>, ... ),
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where <i>i<FONT SIZE=1.0>k</i></FONT> is an integer, <i>k</i> = 1,2,...
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<max_dims> ::= (<i>i<FONT SIZE=1.0>1</i></FONT>, <i>i<FONT SIZE=1.0>2</i></FONT>, ... ) where <i>i<FONT SIZE=1.0>k</i></FONT> is an integer or H5S_UNLIMITED
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<ds_definition> ::= TBD
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<data> ::= data {TBD}
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<group_member> ::= <named_datatype> | <named_dataspace> | <group> | <dataset> |
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<softlink>
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<named_datatype> ::= DATATYPE "<type_name>" { <compound_type_def>+ }
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<type_name> ::= "<identifier>"
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<named_dataspace> ::= DATASPACE "<dataspace_name>" { ARRAY <current_dims> <max_dims> } |
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DATASPACE "<dataspace_name>" { OTHER <ds_definition>+ }
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<group> ::= GROUP "<group_name>" { <hardlink> } |
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GROUP "<group_name>" { <group_attribute>* <group_member>* }
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<group_name> ::= <identifier>
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<dataset> ::= DATASET "<dataset_name>" { <hardlink> } |
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DATASET "<dataset_name>" { <datatype>
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<dataspace>
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<storagelayout><FONT SIZE=1.7>opt</FONT>
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<compression><FONT SIZE=1.7>opt</FONT>
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<dataset_attribute>*
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<data><FONT SIZE=1.7>opt</FONT> }
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// Tokens within {} can be in any order as long as <data> and <dataset_attribute>
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// are after <datatype> and <dataspace>.
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<dataset_name> ::= <identifier>
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<storagelayout> :: = STORAGELAYOUT <contiguous_layout> |
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STORAGELAYOUT <chunked_layout> |
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STORAGELAYOUT <compact_layout> |
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STORAGELAYOUT <external_layout>
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<contiguous_layout> ::= {CONTIGUOUS} // default
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<chunked_layout> ::= {CHUNKED <dims> }
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<dims> ::= (<i>i<FONT SIZE=1.0>1</i></FONT>, <i>i<FONT SIZE=1.0>2</i></FONT>, ... ), <i>i<FONT SIZE=1.0>k</i></FONT> is an integer, <i>k</i> = 1,2,...
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<compact_layout> ::= TBD
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<external_layout> ::= {EXTERNAL <external_file>+ }
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<external_file> ::= (<file_name> <offset> <size>)
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<offset> ::= an integer
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<size> ::= an integer
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<compression> :: = COMPRESSION { TBD }
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<dataset_attribute> ::= <attribute>
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<softlink> ::= SOFTLINK "<softlink_name>" { LINKTARGET "<target>" }
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<softlink_name> ::= <identifier>
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<target> ::= <identifier>
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<identifier> ::= string
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// character '/' should be used with care.
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</PRE>
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</dir>
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<h2>4. An Example of an HDF5 File in DDL</h2>
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<dir>
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<PRE>
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HDF5 "example.h5" {
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GROUP "/" {
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DATASET "dset1" {
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DATATYPE {
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H5T_STD_I32BE int_name;
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H5T_IEEE_F32BE float_name;
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H5T_IEEE_F64BE double_name;
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}
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DATASPACE { ARRAY ( 5 ) ( 5 ) }
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DATA {{0,0,1}, {1,1,0.5}, {2,4,0.333333}, {3,9,0.25}, {4,16,0.2}}
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}
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GROUP "group1" {
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DATASET "dset2" {
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DATATYPE {
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HARDLINK { "/type1" }
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}
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DATASPACE { ARRAY ( 5 ) ( 5 ) }
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DATA {{0,0}, {1,1.1}, {2,2.2}, {3,3.3}, {4,4.4}}
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}
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}
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GROUP "group2" {
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HARDLINK { "/group1" }
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}
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SOFTLINK "slink1" {
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LINKTARGET "somevalue"
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}
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DATATYPE "type1" {
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H5T_STD_I32BE int_name;
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H5T_IEEE_F32BE float_name;
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}
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}
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}
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</pre>
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</dir>
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<hr>
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<address>
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<a href="mailto:hdfhelp@ncsa.uiuc.edu">HDF Help Desk</a>
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</address>
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Last modified: 28 October 1998
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</body>
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</html>
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