HPlogo QUERY/iX Reference Manual > Appendix E SELF-DESCRIBING FILES

USER LABELS

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E1098 Edition 6

There are two types of user labels which both contain descriptive information. One type contains global information about the file and the data it contains. The other type contains specific information about each item in the data set entry or compound data set entry in the file. Each user label is 128 words in length and is placed in the file as follows: 

  ----------------------------------------
  |     reserved for existing labels     | 0-9
  ----------------------------------------
  |     last item description label      | 10
  ----------------------------------------
  |      item description label          | 11
  ----------------------------------------
  |      item description label          | 12
  ----------------------------------------
  |      first item description label    | 13
  ----------------------------------------
  |      global information label        | 14
  ----------------------------------------
  |               data                   |
  |                                      |
  ----------------------------------------
Labels are in "reverse" order in the file. That is the last label is the global information label, the second to last label is the first item description label. An item description label contains one or more item descriptions and there must be at least one item description label.

When the file is built, space is reserved for pre-existing user labels. Pre-existing labels may have been placed in the file by an application program. If another application program converts an existing file with user labels into an SD file, the existing labels are not overwritten unless there are more than ten. Pre-existing user labels begin at label 0. As a result, the last item description label always occupies label 10 in the SD file.

Global Information Label Format

The information in the global information label resides in the following order: 

  version | length | #items | #labels | #items/labels | size
version

is the the version of the SD Intrinsics that created the file. The standard HP version format is followed (AA.NN.NN). (8 characters, right justified)

length

is the length of the records in bytes. This corresponds to the size of the IMAGE entry. (integer)

#items

is the number of items in each file record. This corresponds to the number of items in the IMAGE entry. (integer)

#labels

is the number of item description user labels. (integer)

#items/labels

is the number of item descriptions that fit into one item description label. Each label can hold INTEGER (128/size). (integer)

size

is the size of one item description in words. (integer)

Item Description Label Format

The information in the item description label resides in the following order: 

  itemname | itemtype | itemoffset | itemlength | reservedspace
item name

is the name of the item. (16 characters, left justified)

item type

is one of the following codes indicating the type of item. (integer) 


       1 = ASCII  (type U and X)
       2 = ASCII numeric in free form
       3 = signed integer  (type I)
       4 = floating point real  (type R)
       5 = packed decimal  (type P)
       6 = COBOL computational  (type J)
       7 = unsigned integers  (type K)
       8 = zoned decimal  (type Z)
       9 = IEEE floating point real (type E)
      10 = IMAGE compound item
The item types in parentheses correspond to IMAGE data types.

Note: Type 2 refers to ASCII representations of numbers in free format. This includes 20, 45.7, 1.002E-10, -201.45.

item offset

is the offset of the item in the file record in bytes. This offset is relative to the beginning of the beginning of a record where the first byte has an offset of zero, the second has an offset of one, and so on. (integer)

item length

is the length of the item in bytes. This distinguishes the long and short forms of integers and reals. (integer)

reserved space

is reserved for future enhancements to SD files. Four words are reserved.



FILE DATA

ITEM NAMES