188 lines
6.1 KiB
Groff
188 lines
6.1 KiB
Groff
.\" DO NOT MODIFY THIS FILE! It was generated by help2man 1.022.
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.TH GPERF "1" "September 2000" "GNU gperf 2.7.2" FSF
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.SH NAME
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gperf \- generate a perfect hash function from a key set
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.SH SYNOPSIS
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.B gperf
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[\fIOPTION\fR]... [\fIINPUT-FILE\fR]
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.SH DESCRIPTION
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GNU `gperf' generates perfect hash functions.
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.PP
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If a long option shows an argument as mandatory, then it is mandatory
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for the equivalent short option also.
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.SS "Input file interpretation:"
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.TP
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\fB\-e\fR, \fB\-\-delimiters\fR=\fIDELIMITER\-LIST\fR
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Allow user to provide a string containing delimiters
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used to separate keywords from their attributes.
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Default is ",\en".
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.TP
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\fB\-t\fR, \fB\-\-struct\-type\fR
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Allows the user to include a structured type
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declaration for generated code. Any text before %%
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is considered part of the type declaration. Key
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words and additional fields may follow this, one
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group of fields per line.
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.SS "Language for the output code:"
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.TP
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\fB\-L\fR, \fB\-\-language\fR=\fILANGUAGE\-NAME\fR
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Generates code in the specified language. Languages
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handled are currently C++, ANSI-C, C, and KR-C. The
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default is C.
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.SS "Details in the output code:"
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.TP
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\fB\-K\fR, \fB\-\-slot\-name\fR=\fINAME\fR
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Select name of the keyword component in the keyword
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structure.
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.TP
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\fB\-F\fR, \fB\-\-initializer\-suffix\fR=\fIINITIALIZERS\fR
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Initializers for additional components in the keyword
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structure.
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.TP
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\fB\-H\fR, \fB\-\-hash\-fn\-name\fR=\fINAME\fR
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Specify name of generated hash function. Default is
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`hash'.
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.TP
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\fB\-N\fR, \fB\-\-lookup\-fn\-name\fR=\fINAME\fR
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Specify name of generated lookup function. Default
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name is `in_word_set'.
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.TP
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\fB\-Z\fR, \fB\-\-class\-name\fR=\fINAME\fR
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Specify name of generated C++ class. Default name is
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`Perfect_Hash'.
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.TP
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\fB\-7\fR, \fB\-\-seven\-bit\fR
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Assume 7-bit characters.
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.TP
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\fB\-c\fR, \fB\-\-compare\-strncmp\fR
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Generate comparison code using strncmp rather than
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strcmp.
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.TP
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\fB\-C\fR, \fB\-\-readonly\-tables\fR
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Make the contents of generated lookup tables
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constant, i.e., readonly.
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.TP
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\fB\-E\fR, \fB\-\-enum\fR
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Define constant values using an enum local to the
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lookup function rather than with defines.
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.TP
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\fB\-I\fR, \fB\-\-includes\fR
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Include the necessary system include file <string.h>
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at the beginning of the code.
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.TP
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\fB\-G\fR, \fB\-\-global\fR
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Generate the static table of keywords as a static
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global variable, rather than hiding it inside of the
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lookup function (which is the default behavior).
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.TP
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\fB\-W\fR, \fB\-\-word\-array\-name\fR=\fINAME\fR
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Specify name of word list array. Default name is
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`wordlist'.
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.TP
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\fB\-S\fR, \fB\-\-switch\fR=\fICOUNT\fR
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Causes the generated C code to use a switch
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statement scheme, rather than an array lookup table.
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This can lead to a reduction in both time and space
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requirements for some keyfiles. The COUNT argument
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determines how many switch statements are generated.
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A value of 1 generates 1 switch containing all the
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elements, a value of 2 generates 2 tables with 1/2
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the elements in each table, etc. If COUNT is very
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large, say 1000000, the generated C code does a
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binary search.
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.TP
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\fB\-T\fR, \fB\-\-omit\-struct\-type\fR
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Prevents the transfer of the type declaration to the
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output file. Use this option if the type is already
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defined elsewhere.
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.SS "Algorithm employed by gperf:"
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.TP
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\fB\-k\fR, \fB\-\-key\-positions\fR=\fIKEYS\fR
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Select the key positions used in the hash function.
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The allowable choices range between 1-126, inclusive.
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The positions are separated by commas, ranges may be
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used, and key positions may occur in any order.
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Also, the meta-character '*' causes the generated
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hash function to consider ALL key positions, and $
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indicates the ``final character'' of a key, e.g.,
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$,1,2,4,6-10.
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.TP
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\fB\-l\fR, \fB\-\-compare\-strlen\fR
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Compare key lengths before trying a string
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comparison. This helps cut down on the number of
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string comparisons made during the lookup.
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.TP
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\fB\-D\fR, \fB\-\-duplicates\fR
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Handle keywords that hash to duplicate values. This
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is useful for certain highly redundant keyword sets.
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.TP
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\fB\-f\fR, \fB\-\-fast\fR=\fIITERATIONS\fR
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Generate the gen-perf.hash function ``fast''. This
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decreases gperf's running time at the cost of
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minimizing generated table size. The numeric
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argument represents the number of times to iterate
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when resolving a collision. `0' means ``iterate by
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the number of keywords''.
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.TP
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\fB\-i\fR, \fB\-\-initial\-asso\fR=\fIN\fR
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Provide an initial value for the associate values
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array. Default is 0. Setting this value larger helps
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inflate the size of the final table.
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.TP
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\fB\-j\fR, \fB\-\-jump\fR=\fIJUMP\-VALUE\fR
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Affects the ``jump value'', i.e., how far to advance
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the associated character value upon collisions. Must
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be an odd number, default is 5.
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.TP
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\fB\-n\fR, \fB\-\-no\-strlen\fR
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Do not include the length of the keyword when
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computing the hash function.
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.TP
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\fB\-o\fR, \fB\-\-occurrence\-sort\fR
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Reorders input keys by frequency of occurrence of
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the key sets. This should decrease the search time
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dramatically.
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.TP
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\fB\-r\fR, \fB\-\-random\fR
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Utilizes randomness to initialize the associated
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values table.
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.TP
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\fB\-s\fR, \fB\-\-size\-multiple\fR=\fIN\fR
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Affects the size of the generated hash table. The
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numeric argument N indicates ``how many times larger
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or smaller'' the associated value range should be,
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in relationship to the number of keys, e.g. a value
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of 3 means ``allow the maximum associated value to
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be about 3 times larger than the number of input
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keys.'' Conversely, a value of \fB\-3\fR means ``make the
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maximum associated value about 3 times smaller than
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the number of input keys. A larger table should
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decrease the time required for an unsuccessful
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search, at the expense of extra table space. Default
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value is 1.
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.SS "Informative output:"
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.TP
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\fB\-h\fR, \fB\-\-help\fR
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Print this message.
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.TP
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\fB\-v\fR, \fB\-\-version\fR
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Print the gperf version number.
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.TP
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\fB\-d\fR, \fB\-\-debug\fR
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Enables the debugging option (produces verbose
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output to the standard error).
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.SH "REPORTING BUGS"
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Report bugs to <bug-gnu-utils@gnu.org>.
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.SH "SEE ALSO"
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The full documentation for
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.B gperf
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is maintained as a Texinfo manual. If the
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.B info
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and
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.B gperf
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programs are properly installed at your site, the command
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.IP
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.B info gperf
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.PP
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should give you access to the complete manual.
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