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A.5 rVariables Section

The rVariables section contains the definition of each rVariable in the CDF, the values for any vAttribute rEntries associated with each rVariable, and (optionally) data values for those rVariables. The format of the rVariables section is as follows:

#variables

[<variable-definition>
 <variable-definition>
 <variable-definition>
           .
           .
           .
 <variable-definition>]

Where <variable-definition> is an rVariable definition. The format of each rVariable definition is as follows:

! Variable            Data         Number     Record     Dimension
! Name                Type        Elements   Variance    Variances        
! --------            ----        --------   --------    ---------

  <var-name>     <var-data-type>  <n-elems> <rec-vary>  <dim-varys>

  !  Attribute           Data
  !  Name                Type           Value
  !  ---------           ----           -----

     [<attr-name>  <entry-data-type>    <entry-value>
      <attr-name>  <entry-data-type>    <entry-value>
      <attr-name>  <entry-data-type>    <entry-value>
           .               .                  .
           .               .                  .
           .               .                  .
      <attr-name>  <entry-data-type>    <entry-value>].         ! Note the "."

   [[<rec-num>:]<indices> = <value>
    [<rec-num>:]<indices> = <value>
    [<rec-num>:]<indices> = <value>
        .            .
        .            .
        .            .
    [<rec-num>:]<indices> = <value>]

Each field is defined as follows:

<var-name>

The name of the rVariable. The name must be delimited with a character not appearing in the name itself (e.g., "EPOCH" or 'Temperature'). The delimiting characters are not part of the rVariable name in the CDF.

<var-data-type>

The data type for the rVariable. The data type must be one of the following: CDF_BYTE, CDF_INT1, CDF_UINT1, CDF_INT2, CDF_UINT2, CDF_INT4, CDF_UINT4, CDF_REAL4, CDF_FLOAT, CDF_REAL8, CDF_DOUBLE, CDF_EPOCH, CDF_CHAR, or CDF_UCHAR.

<n-elems>

The number of elements of the data type. For character string data types ( CDF_CHAR and CDF_UCHAR), this is the number of characters in each string. For non-character string data types, this value must be one (1).

<rec-vary>

The record variance of the rVariable. This must be either T (the values vary from record to record) or F (the values do not vary from record to record).

<dim-varys>

The dimension variances of the rVariable. For each dimension there must be either a T (the values vary along that dimension) or F (the values do not vary along that dimension). Each dimension variance must be separated by at least one space. If the rVariables have zero dimensions, this field would be left blank.

<attr-name>

The name of the vAttribute for which to specify an rEntry for this rVariable. The vAttribute must have been specified in the vAttributes section. The name must be delimited with a character not appearing in the name itself (e.g., "SCALEMAX" or 'range'). The delimiting characters are not part of the vAttribute name in the CDF.

<entry-data-type>

The data type for the vAttribute rEntry. The data type must be one of the following: CDF_BYTE, CDF_INT1, CDF_UINT1, CDF_INT2, CDF_UINT2, CDF_INT4, CDF_UINT4, CDF_REAL4, CDF_FLOAT, CDF_REAL8, CDF_DOUBLE, CDF_EPOCH, CDF_CHAR, or CDF_UCHAR.

<entry-value>

The value(s) for the vAttribute rEntry. The format of attribute entry values is described in Section A.3. NOTE: The last rEntry MUST be followed by a period ( .). If no rEntries are specified for an rVariable, the period must still be present.

<rec-num>

The record number of an rVariable value. This will be present only for record-variant (RV) rVariables.

<indices>

The indices of an rVariable value. The indices are enclosed in brackets and separated by commas (e.g., [23,1] or [1,80]). If the rVariables have zero dimensions, [] would be specified (the brackets are still required).

<value>

The value at the given record/indices. For character string data types ( CDF_CHAR or CDF_UCHAR) the string must be delimited with a unique character and enclosed in braces ( {...}) in the same manner as for an attribute entry for a character string data type. For non-character string data types the value is not enclosed in braces (the braces are not necessary because there can only be one element). The format for CDF_EPOCH values is described in Section 2.2.10.

The vAttribute rEntries are optional. If omitted, the terminating period is still required. The rVariable values are also optional. Several sample rVariable definitions for a CDF with 2-dimensional rVariables follow: ! Variable Data Number Record Dimension ! Name Type Elements Variance Variances ! -------- ---- -------- -------- --------- "Latitude" CDF_REAL4 1 F F T ! Attribute Data ! Name Type Value ! -------- ---- ----- "VALIDMIN" CDF_REAL4 { -90.0 } "VALIDMAX" CDF_REAL4 { 90.0 } "scale" CDF_REAL4 { -60.0, 60.0 }. [1,1] = -60.0 [1,2] = -30.0 [1,3] = 0.0 [1,4] = 30.0 [1,5] = 60.0 ! Variable Data Number Record Dimension ! Name Type Elements Variance Variances ! -------- ---- -------- -------- --------- "EPOCH" CDF_EPOCH 1 T F F ! Attribute Data ! Name Type Value ! -------- ---- ----- "scale" CDF_EPOCH { 10-Oct-1991 00:00:00.000, 20-Oct-1991 23:59:59.999 }. ! Variable Data Number Record Dimension ! Name Type Elements Variance Variances ! -------- ---- -------- -------- --------- 'Tmp' CDF_INT2 1 T T T ! Attribute Data ! Name Type Value ! -------- ---- ----- 'Fieldname' CDF_CHAR { "Temperature (C)" }. ! Variable Data Number Record Dimension ! Name Type Elements Variance Variances ! -------- ---- -------- -------- --------- "Pres_lvl" CDF_REAL4 1 T F F ! Attribute Data ! Name Type Value ! -------- ---- ----- . ! no attribute entries 1:[1,1] = 1013.1 2:[1,1] = 1015.0 3:[1,1] = 1012.3 A sample variable definition for a CDF with 0-dimensional rVariables follows: ! Variable Data Number Record Dimension ! Name Type Elements Variance Variances ! -------- ---- -------- -------- --------- "Latitude" CDF_REAL4 1 F ! Attribute Data ! Name Type Value ! -------- ---- ----- "VALIDMIN" CDF_REAL4 { -90.0 } "VALIDMAX" CDF_REAL4 { 90.0 }. [] = -12.3

Next: A.6 zVariables Section Up: A Skeleton Table Format Previous: A.4 vAttributes Section

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