COMMON METADATA

Name of GeM+ entry: Content maintenance
Name of REL file key: ContentMaintenance

Description and considerations: The frequency with which changes or updates are made to the content of the database once it is complete.

Follows the proposal of: ISO

Obligatory according to ISO: No

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information from the Layer)

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Name of GeM+ entry: Content date
Name of REL file key: ContentDate

Description and considerations: Date of the content of the database, or rather the date of the values contained in the database. For example, the date of the field data from which the database has been created. It may be a single date or a time interval.

Consult the considerations on dates and times.

Follows the proposal of: FDGC

Obligatory according to the FGDC: Yes

Cardinality: 1

Key type: N

AppliesToLayer: Yes
AppliesToSeries: No (contains information from the Layer)

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REL FILE METADATA

Name of GeM+ entry: Metadata version
Name of the REL file key:
VersMetaDades and SubVersMetaDades

Description and considerations: The version and subversion of the metadata. The version number is shown followed by a decimal point and the subversion number, following the usual convention for version numbering.

If the REL file keys indicate:

VersMetaDades=4
SubVersMetaDades=0

then GeM+ will show: "Metadata version: 4.0".

Follows the proposal of: GeM+

Obligatory according to GeM+: Yes

Cardinality: 1

Type of key: N

AppliesToLayer: Yes
AppliesToSeries: No (contains information about the Layer)

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Name of GeM+ entry: Relations table version
Name of the REL file key:
Vers and SubVers

Description and considerations: Version and subversion of the relations between the tables. The version number is shown followed by a decimal point and the subversion number, following the usual convention for version numbering.

If the REL file keys indicate:

Vers=4
SubVers=0

the GeM+ will show: "Relations table version: 4.0".

Follows the proposal of: GeM+

Obligatory according to GeM+: Yes

Cardinality: 1

Type of key: N

AppliesToLayer: Yes
AppliesToSeries: No (contains information about the Layer)

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TABLE OR MULTIBAND IMAGE METADATA

Name of GeM+ entry: (not displayed in GeM+)
Name of REL file key: IndexsJoinTaula (see the key in case of raster and vector)

Description and considerations: When a field is associated with a table (join), this key indicates the internal name of each of the tables associated with it, separated by comas. The definitive name of each table is defined in the Table Name key. This information is not displayed (and cannot therefore be changed).

Follows the proposal of: GeM+

Obligatory according to GeM+: Yes

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information from the Layer)

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Name of GeM+ entry: Table Name
Name of REL file key: JoinTaula_NOM_TAULA (see the key for the case of raster and vector)

Description and considerations: Name of the table in the REL file. This name is indicated merely for information, but cannot be changed. It is displayed in the upper part of the area for the metadata that define the table, followed by the table type in parenthesis. Examples:

PRINCIPAL (DBF): Principal table of structured vectors

GENERICA_PRINCIPAL (GENERICA): Multiband image in the case of rasters

TESAURUS_MUNICIPIS (ODBC): Associated table

The names of the principal table of a structured vector and of a multiband image are predefined (see above examples). The names of the associated tables are defined when links are made from the original field of the table.

The table name should be unique for all the tables to which links are made from the same REL file, since it is used to form the name of the section that will define the properties of the table. Note, however, that the physical names of the tables may not be unique since this key can be used to avoid a problem. If we suppose, for example, that we have two tables on two different database servers, in two different directories, and both are called "dictionary", then when the two become part of the same relations tree for a layer it will be necessary, in the context of GeM+, to call one, for instance, "dictionary_municipalities" and the other "dictionary_districts".

Follows the proposal of: GeM+

Obligatory according to GeM+: Yes

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information from the Layer)

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Name of GeM+ entry: Number of registers
Name of REL file key: (not stored in the REL file, it is deduced dynamically)

Description and considerations: This is the number of registers that are contained in the table that is being defined. It does not apply to tables that are multiband images.

Follows the proposal of: GeM+

Obligatory according to GeM+: It is deduced dynamically.

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information from the Layer)

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Name of GeM+ entry: Number of fields or bands
Name of REL file key: (not stored in the REL file, it is deduced dynamically)

Description and considerations: This is the number of fields in the table or bands in a multiband image. It is deduced dynamically and cannot be changed. To change the structure of a DBF or ODBC table it is necessary to use the Table Manager of the corresponding database. To modify the structure of a multiband image use the tools provided for adding and removing bands.

Follows the proposal of: GeM+

Obligatory according to GeM+: It is deduced dynamically.

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information from the Layer)

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FIELD OR BAND METADATA

Name of GeM+ entry: Band
Name of the REL file key:
NomFitxer

Description and considerations: The name of the binary file corresponding to this field or band. Typically used for multi-band rasters with a single documentation file in which each [ATTRIBUTE_DATA:NOM_CAMP] section contains the NomFitxer (File name) key. Only applies to multi-band rasters.

In general it makes no sense to consider the most frequently occurring file name (the mode) since each name is unique to each field, so this key is never written in the ([ATTRIBUTE_DATA]) general section and only appears in the band specific sections ([ATTRIBUTE_DATA:NOM_CAMP]). There is a single case where this key may be used with a general value: in multi-band files, like JPEG 24 bit colour files, in which a single binary file contains more than one spectral channel and more than one [ATTRIBUTE_DATA:NOM_CAMP] section. In this case the key (e.g. orto534.jpg) is written in the general section and not in the various field sections (to avoid repetition).

In the GeM+ the file names are visible from any of the tags since they are in the pull-down list located in the upper part. This pull-down list (and the forward (>) and back (<) buttons next to it) allow selection of the fields for which the specific data are to be displayed. It is only possible to see the specific data of one field (band) at a time.

Although this key is only saved in the REL file for multi-band rasters, the pull-down list with the different band names that make up the multi-band layer is displayed in GeM+ for all types of layers since the layer name for which the metadata are being edited is always shown.

In GeM+ this entry is shown together with the spectral channel since the pull-down list shows the file name and, in those cases where it is necessary, the spectral channel number in brackets.

Follows the proposal of: GeM+

Obligatory according to GeM+: Yes in multi-band rasters. In single band rasters or vectors it is not needed since the file name can be deduced from the REL file name.

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information about the Layer)

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Name of GeM+ entry: Channel
Name of the REL file key:
canal

Description and considerations: In the raster formats that can store more than one band in the same file, such as JPEG 24 bit color or BIL type formats, the "channel" key indicates which band of the binary file is described by the [ATRIBUTTE_DATA:NOM_CAMP] that is being edited.

May take values from 1 to n (where n is the number of bands in the multi-band format). In this way each field (band) of a multi-band layer is uniquely identified by the two keys: "File Name" and "Channel", even for the case where the same layer (REL file) refers to more than one multi-band file (e.g. two JPEG 24 bit color files).

Only applies to raster formats with one or more multi-band files (e.g. in a JPEG 24 bit color, JPEG2000 or MrSID multispectral format).

In GeM+ this entry is shown together with the Band since the pull-down list shows the file name and, where necessary, the channel number in brackets.

Follows the proposal of: GeM+

Obligatory according to GeM+: Yes in rasters with multi-band files.

Cardinality: 1

Key type: N

AppliesToLayer: Yes
AppliesToSeries:No (contains information about the Layer)

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Name of GeM+ entry: (not displayed in GeM+)
Name of the REL file key:
IndexsNomsCamps

Description and considerations: Indicates the index of all the bands, separated by commas. The definitive alias of each band is defined in the Name key (that would be equivalent to the names of the fields in the database).

This information is not displayed and cannot therefore be modified. Should the band index be missing (for example, when a file is created from scratch) on saving GeM+ assigns numbers from 1 to n to the band indices.

Follows the proposal of: GeM+

Obligatory according to GeM+: Yes

Cardinality:1

Key type:C

AppliesToLayer: Yes
AppliesToSeries: No (contains information on the Layer)

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Name of GeM+ entry:
Name
Name of the REL file key:
NomCamp_NOM_CAMP (in the REL it is only stored for raster files)

Description and considerations: In the CSDGM standard of the FGDC it is defined as "the name of the attribute" (key name in the FGDC standard: Attribute Label). Corresponds to the name of the attribute whether the attribute is a field in a database (the principal table or associated table of a structured vector) or whether it is the value of a band of a multiband image.

The following two cases may occur:

In the REL file this key is found in the [ATTRIBUTE_DATA] section where, for example, the following might be seen:

[ATTRIBUTE_DATA]
IndexsNomsCamps=R,IRp
NomCamp_R=CANAL_ROJO
NomCamp_IRp=CANAL_INFRARROJO_CERCANO
[ATTRIBUTE_DATA:
CANAL_ROJO]
...
[ATTRIBUTE_DATA:
CANAL_INFRARROJO_CERCANO]
...

Follows the proposal of: The FGDC

Obligatory according to the FGDC: Yes for rasters. For database fields it is deduced dynamically

Cardinality:1

Key type:C

AppliesToLayer: Yes
AppliesToSeries: No (contains information about the Layer)

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Name of GeM+ entry: Description
Name of the REL file key: descriptor
(see the key in case of raster and vector)

Description and considerations: Description of the content of the band or field (analagous to the "descriptor=" key in the database). In the CSDGM standard of the FGDC it is defined as "the description of the attribute" (key name in the FGDC standard: Attribute Definition).

Note that the fields in conventional database fields have an implicit key "name=" that is not really found in the REL file but rather it is found in the header of the table file or within the database manager where it acts as an internal name. This name is NOT synonymous with the "descriptor=" key, although they do correspond when "descriptor=" is not present in the metadata file (that is, when there is no description the internal name is used).

The band name in each band of a single band or multi-band raster is provided by the "NomCamp_XXX=" key in [ATTRIBUTE_DATA].

In the case of automatic transformation of the older documentation files various entries in the documentation file may be assigned to the description as a function of the type of raster being documented:

For multi-band layers the band description is concatenated to the Dataset Title so that it can be shown in the MiraMon title bar.

Follows the proposal of: The FGDC

Obligatory according to the FGDC: Yes

Cardinality:1

Key type:C

AppliesToLayer: Yes
AppliesToSeries: Yes

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Name of GeM+ entry: Data type and Compressed file
Name of the REL file key: TipusCompressio (not stored in the formats indicated in the file header)

Description and considerations: The TipusCompressio (Compression type) key of the REL file simultaneously indicates the type of data contained in the raster or the unstructured vector file and its compression type. Some examples of valid values in the REL file are: "byte", "byte-RLE", etc. This key is equivalent to the "data type entry : " in the older documentation files.

In GeM+ the data type and the compression type are presented separately. For the data type it is necessary to select the desired data type from a pull-down list. The possible data types will vary depending on whether the layer to be documented is a raster or an unstructured vector.

For rasters the possible values are:

and, for unstructured vectors:

With regards to the compression it is necessary to indicate whether the raster is stored using some compression algorithm. In MiraMon compressed files a modified Run Length Encoding (RLE) technique is used. This is described in the image processing and remote sensing bibliography. MiraMon unstructured vector files cannot be compressed.

In the file types that give information in the header on the data type and file compression (e.g. JPEG, JPEG2000 or MrSID formats) this metadata entry is only indicative. The user may not change the value nor can the information be stored in the REL file.

Follows the proposal of: GeM+

Obligatory according to GeM+: Yes.

Cardinality:1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information about the Layer)

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Name of GeM+ entry: Type, Size and Decimals
Name of REL file key: (not stored in the REL file, it is deduced dynamically)

Description and considerations: These three entries define the format of the fields in the DBF table, or other tables accessible via ODBC. The number of decimals is only applied when the field type is numeric.

This information is stored in the headers of the DBF or can be obtained from the database manager so they are not stored in the REL file nor can they be changed from GeM+. To change these values it is necessary to use a database manager.

Follows the proposal of: GeM+

Obligatory according to GeM+: Deduced dynamically.

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information from the Layer)

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Name of GeM+ entry: Treatment of the variable
Name of the REL file key: TractamentVariable (see the key in case of raster and vector)

Description and considerations: Indicates how the field values should be treated (in the case of rasters and non-estructured vectors they are the values found in the graphics file). The possible values of this key are:

In the case of classified rasters they are converted to a table (typically in DBF format) which is associated with the raster field. For the case of automatic transformation of the older documentation files a table is created with two fields; VALUE and CATEGORY, the first containing all the raster values that are different from NODATA and that have a description (ordered without repetition), and the second containing the description itself.

The "value units" entry of the older documentation files is restored as a CATEGORY field description

In the case where the treatment of the variable is changed in order to document as classified a raster that previously was not classified, then GeM+ creates a database with the same structure containing all the values between the minimum and maximum values documented (and different from the NODATA value) and without any description in the CATEGORY field.

Follows the proposal of: GeM+

Obligatory according to GeM+: No.

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: Yes

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Name of GeM+ entry: Units of the variable
Name of the REL file key: unitats (see the key in case of raster and vector)

Description and considerations: The measurement units of the values in the image (band) or the field. This will be read only if the Treatment of the variable is Continuous Quantitative.

May take any value but some values have become normalised:

· Unknown units (represented by "?")
· No units (represented by an empty string or a blank " ")
· User-defined units: "m" for metres, etc.

The user can select from these normalised values or enter any other text.

In the case of continuous rasters it corresponds to the "ValueUnits" entry of the older documentation files.

value units : DN [ATTRIBUTE_DATA]
unitats=DN

In the case of classified rasters the "ValueUnits" entry of the older documentation files is converted into the Band description and the units entry is not read.

The older documentation files of the unstructured vectors do not contain any "ValueUnits" entry.

Follows the proposal of: GeM+

Obligatory according to GeM+: Yes, if apt.

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries:
Yes

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Name of GeM+ entry: Show units
Name of the REL file key: MostrarUnitats (see the key in case of raster and vector)

Description and considerations: This entry indicates whether the user wishes to show the units of a band when carrying out a query. It may be 0 (false, the default value if the Units key is "No units") or 1 (true, the default value if there is some string defined as the units, e.g. "m" or "?", meaning "Unknown units"). As occurs with the database field, "Show units" are only read if the Treatment of the variable field is Continuous Quantitative.

Follows the proposal of: GeM+

Obligatory according to GeM+: No.

Cardinality: 1

Key type: L

AppliesToLayer: Yes
AppliesToSeries: Yes

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Name of GeM+ entry: Show in queries
Name of REL file key: visible (see the key for raster and vector)

Description and considerations: This entry allows the user to choose whether to display the field value or the band in location and attribute queries.

"Show in queries" can take the following values:

For location and for attribute queries
For location (if it has content) and for attribute queries
Do not show

The fields that are related to other tables are never shown (the GeM+ shows "Link to table/s") since the fields shown in queries are those situated in the associated tables through this field.


Follows the proposal of: GeM+

Obligatory according to GeM+: No.

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information from the Layer)

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Name of GeM+ entry: Separator
Name of the REL file key: -SEPARA- (see the key in case of raster and vector)

Description and considerations: Text string for separating the field (or band) data from the rest of the data from a location query, for an easier database query (separating different information with a space, title, symbols, etc.). Can only be defined for visible fields (see entry visible/can be queried).

It is important to distinguish between the cases of when there is no separator (the key is not present in the REL file) and the case when the key has no assigned value. If the key has the value "-SEPARA-= " in the REL file, it is understood that a simple carriage return is wanted between this field and the rest. If the key is not present then it is understood that no separator is needed.

It is possible to define the separator following two types of separator format: plane text and preformated HTML format text (some commands). For the case of HTML type separators, internally the separator starts with <html> and ends with </html>.

Supported HTML commands:

- Font: <FONT COLOR=\"#??????\" FACE=\"??\" SIZE=\"??\">, for example "Arial red size 12" will be set by: <font face="Arial" size="2" color="#FF0000">. Remember that the size of the formats in HTML does not correspond to the usual Windows formats.
- Bold: <B>
- Italics: <I>
- Underline: <U>
- Carriage return: <BR> (without spaces between lines)
- New paragraph: <P> (double space between lines)

The Manager provides tools for using these commands in a simple way.

Follows the proposal of: GeM+

Obligatory according to GeM+: No

Cardinality:1

Key type:C

AppliesToLayer: Yes
AppliesToSeries: Yes

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Name of GeM+ entry: Can be represented by symbols
Name of REL file key: simbolitzable (in the case of raster it is not saved in the REL file)

Description and considerations: Indicates if a field or band can displayed using symbols. This is always the case for rasters.

Follows the proposal of: GeM+

Obligatory according to GeM+: No.

Cardinality: 1

Key type: L

AppliesToLayer: Yes
AppliesToSeries: No (contains information from the Layer)

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Name of GeM+ entry: Quality
Name of the REL file section: [ATTRIBUTE_DATA:NOM:QUALITY] (rasters) or [NOM_TAULA:NOM:QUALITY] (vectors)

Description and considerations: In this section are found the quality parameters of the field (or band) values. Consult the Quality - Parameters section for more general information on the structure of the quality parameter keys.

This section restores the "value error" entry of the older documentation files as this value is converted into a measure of the field quality. The type of measure into which the "value error" entry can be assimilated depends on the type of data being documented:

Follows the proposal of: GeM+

Obligatory according to GeM+: No

Cardinality:1

Key type:Composed

AppliesToLayer: Yes
AppliesToSeries: No (contains information about the Layer)

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Information common to the Minimum value and Maximum value keys.

These keys will be read independently of the value of "TractamentVariable=" (treatment of the variable), since even when this key indicates "Classified" it is useful to know, a priori, the extreme values.

GeM+ has a "calculate" button that allows the real minimum and maximum values in the binary file to be found (without considering the documented NODATA value).

Although in general it is not advisable, MiraMon allows the documented extreme value (of the image or the database field) to differ from the real extreme value.

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Name of GeM+ entry: Minimum value
Name of the REL file key:
min (currently only for rasters)

Description and considerations: The minimum value of the image or database field. Only applies to numerical data. Corresponds to the "min. value" entry in the older documentation files. Currently only implemented for rasters.

See complementary information, common to the Minimum value and Maximum value keys .

Follows the proposal of: GeM+

Obligatory according to GeM+: Yes

Cardinality: 1

Key type: F

AppliesToLayer: Yes
AppliesToSeries:
No (contains information on the Layer)

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Name of GeM+ entry: Maximum value
Name of the REL file key:
max (currently only for rasters)

Description and considerations: The maximum value of the image or database field. Only applies to numerical data. Corresponds to the "max. value" entry in the older documentation files. Currently only implemented for rasters.

See complementary information, common to the Minimum value and Maximum value keys.

Follows the proposal of: GeM+

Obligatory according to GeM+: Yes

Cardinality: 1

Key type: F

AppliesToLayer: Yes
AppliesToSeries:
No

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Name of GeM+ entry: NODATA present
Name of the REL file key: HiHaNODATA (currently only for rasters)

Description and considerations: A logical value that indicates whether or not there exists a value that acts as NODATA. In rasters this will be TRUE only if the the "flag value" entry in the older documentation files is a numerical value. Does not apply to unstructured vectors because this entry did not exist. In structured vectors it is considered that the database fields can always have a NODATA, which is equivalent in this case to the absence of a value.

Follows the proposal of: GeM+

Obligatory according to GeM+: Yes.

Cardinality: 1

Key type: L

AppliesToLayer: Yes
AppliesToSeries: Yes

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Name of GeM+ entry: NODATA value
Name of the REL file key: NODATA (currently only for rasters)

Description and considerations: NODATA value or background value, that can be defined as that field or band value which does not constitute a value in itself. Its name indicates this (NODATA) but it is rather a "floor" of values that form the "background" of the image and can only "be seen" when there is no known value in the cell (background value).

A clear example of this concept would be in a raster that stored terrain elevation, where a NODATA value would indicate where there are no data available for an area, for instance, because it is a maritime area (and bathymetric information is not available) or because it is outside the study area and values are not known for elevations in this region.

It is recommend to use a background value that is outside the range of real values of the image (outside the range between the minimum and maximum values) and that it is a characteristic value within the range of values. For example, in byte images (range 0 to 255) the background value is usually 0 or 255, and in integer images it is usually the value -32768 (range -32768 to 32767).

Currently the background value, or NODATA, can only be saved for raster type data but it is planned to implement its documentation also for all table fields (principal or associated) related to the structured vector field. Currently the traditional convention of database managers is followed where an empty field signifies a NODATA value. It is certain that it could be interesting to have an empty chain (or full of spaces) as a valid value in C type fields, distinguishing the known data entries but the same as an empty string from those for which there are really data (background or NODATA). For this it would be necessary to expand the NODATA value in the vector files to allow the correct differentiation in these cases.

Follows the proposal of: GeM+

Obligatory according to GeM+: Yes.

Cardinality: 1

Key type: F

AppliesToLayer: Yes
AppliesToSeries: Yes

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Name of GeM+ entry: NODATA Definition
Name of the REL file key: NODATADef

Description and considerations: Defines the meaning of the NODATA value, like for instance: "Data not available" or "Outside study area ".

Currently the background, or NODATA, value can only be saved for raster type data. In the vector type data its description coincides with its value (empty string).

Follows the proposal of: GeM+

Obligatory according to GeM+: Yes.

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: Yes

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Name of GeM+ entry: Radiometry
Name of REL file section: [ATTRIBUTE_DATA:NOM:BAND]

Description and considerations: In the case of rasters derived from remote sensing images it can be interesting to save the information refering to the image acquisition conditions (minimum and maximum wavelengths of the sensor, calibration type, radiance calibration coefficients, etc.). See the information in the Radiometry section.

Follows the proposal of: GeM+

Obligatory according to GeM+: No.

Cardinality: 1

Key type: Composed

AppliesToLayer: Yes
AppliesToSeries: No (contains information from the Layer)

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