An encoded value or values. The encoding may utilize
any of several xsd encodings. Something external to the value must
define the encoding. The uom attribute is optional because the value may
be a string or unitless quantity. If the value is a measure then
the uom must be specified.
A generic measure type.
This should not be used except in situations where the underlying class of data is
captured elsewhere. For example, for a log curve.
A measured depth coordinate in a wellbore.
Positive moving from the reference datum toward the bottomhole.
All coordinates with the same datum (and same uom) can be considered to be in the same
Coordinate Reference System and are thus directly comparable.
'A pointer to the reference datum for this coordinate value as defined in WellDatum. This value is assumed to match the uid value in a WellDatum. If not given then the default WellDatum must be assumed.'
Representation of a number as a double, possibly qualified as a ratio of doubles.
Ratio component attributes 'numerator' and 'denominator' may be both present or both absent.
When ratio component attributes are present, the ratio represented is to be used with
the double representation included for human readability.
A 'canonical' representation, according to the following rules, is suggested:
Only use numerator/denominator when the representation of the number as double is not
sufficiently precise (i. e. causes errors of accumulation).
Express both numerator and denominator as integers (doubles with integer values) reduced
to 'least common denominator' if possible.
'A reference to the unique identifier (uid attribute) in the node referenced by the name value. This attribute is required within the context of a WITSML server.'
A reference to a name in another object.
This value represents a foreign key from one object to another.
Knowledge of the object being referenced is defined by an attribute.
'A reference to the unique identifier (uid attribute) in the object referenced by the name value. This attribute is required within the context of a WITSML server.'
'A reference to the unique identifier (uid attribute) in the node referenced by the index value. This attribute is required within the context of a WITSML server.'
A type with a classType attribute. This allows a user to give a
classification of something, and to specify the type of classification that it is.
There is no control over the class values, or the class types.
A vertical (gravity based) elevation coordinate within the context of a well.
Positive moving upward from the reference datum.
All coordinates with the same datum (and same uom) can be considered to be in the same
Coordinate Reference System and are thus directly comparable.
'The unit of measure of the quantity value. If not given then the default unit of measure of the explicitly or implicitly given datum must be assumed.'
A vertical (gravity based) depth coordinate within the context of a well.
Positive moving downward from the reference datum.
All coordinates with the same datum (and same uom) can be considered to be in the same
Coordinate Reference System and are thus directly comparable.
A comment or remark intended for human consumption.
There should be no assumption that semantics can be extracted from this field by a computer.
Neither should there be an assumption that any two humans will interpret the information
in the same way (i.e., it may not be interoperable).
A community assigned human recognizable name.
This type of value is intended to be unique and is generally a candidate to be constrained to an enumerated list.
A user assigned human recognizable contextual name of something.
There should be no assumption that (interoperable) semantic information will be extracted from the name by a third party.
This type of value is generally not guaranteed to be unique and is not a candidate to be replaced by an enumeration.
A non-negative integer (zero based count or index) with a maximum value of 32767 (2-bytes).
For items that represent "number of" something or a "sequential" count or index.
A reference to the unique identifier of another element.
This value represents a foreign key from one element to another.
The value should match the value of an attribute of type uidString.
A reference to a wellDatum in the current well.
This value must match the uid value in a WellDatum.
This value represents a foreign key from one element to another.
This is an exception to the convention that a foreign key must utilize both
a human contextual name and a uid value. For messages outside the context of
a server then this value will commonly match the value of the name of the
wellDatum (e.g., 'KB') if uids are not not used in that context.
This was a compromise in order to allow the coordinate structures to be simple
and still be usable both within the context of a server and outside the context of a server.
The version of the schema.
The first three levels are fixed. The fourth level can vary
to represent on the constraints defined in enumerations and
XML loader files.
A time zone conforming to the XSD:dateTime specification.
It should be of the form "Z" or "shh.mm" where
"s" is "+" or "-",
"hh" is 00 to 23 and
"mm" is 00 to 59.
A date with the time of day and an optional time zone.
While the time zone is optional, it is strongly advised that the zone
always be specified in each date time value.
A locally unique identifier.
The value is not intended to convey any semantic content (e.g., it may be computer generated).
The value is only required to be unique within a context in a document (e.g., defined via key and keyref).
There is no guarantee that the same data in multiple documents will utilize the same uid value
unless enforced by the source of the document (e.g., a document server).
The XML Instance Representation table above shows the schema component's content as an XML instance.
The minimum and maximum occurrence of elements and attributes are provided in square brackets, e.g. [0..1].
Model group information are shown in gray, e.g. Start Choice ... End Choice.
For type derivations, the elements and attributes that have been added to or changed from the base type's content are shown in bold.
If an element/attribute has a fixed value, the fixed value is shown in green, e.g. country="Australia".
Otherwise, the type of the element/attribute is displayed.
If the element/attribute's type is in the schema, a link is provided to it.
For local simple type definitions, the constraints are displayed in angle brackets, e.g. <<pattern = [1-9][0-9]{3}>>.
If a local element/attribute has documentation, it will be displayed in a window that pops up when the question mark inside the attribute or next to the element is clicked, e.g. <postcode>.
Abstract(Applies to complex type definitions and element declarations). An abstract element or complex type cannot used to validate an element instance. If there is a reference to an abstract element, only element declarations that can substitute the abstract element can be used to validate the instance. For references to abstract type definitions, only derived types can be used.
Collapse Whitespace PolicyReplace tab, line feed, and carriage return characters with space character (Unicode character 32). Then, collapse contiguous sequences of space characters into single space character, and remove leading and trailing space characters.
Disallowed Substitutions(Applies to element declarations). If substitution is specified, then substitution group members cannot be used in place of the given element declaration to validate element instances. If derivation methods, e.g. extension, restriction, are specified, then the given element declaration will not validate element instances that have types derived from the element declaration's type using the specified derivation methods. Normally, element instances can override their declaration's type by specifying an xsi:type attribute.
Nillable(Applies to element declarations). If an element declaration is nillable, instances can use the xsi:nil attribute. The xsi:nil attribute is the boolean attribute, nil, from the http://www.w3.org/2001/XMLSchema-instance namespace. If an element instance has an xsi:nil attribute set to true, it can be left empty, even though its element declaration may have required content.
Prohibited Derivations(Applies to type definitions). Derivation methods that cannot be used to create sub-types from a given type definition.
Prohibited Substitutions(Applies to complex type definitions). Prevents sub-types that have been derived using the specified derivation methods from validating element instances in place of the given type definition.
Replace Whitespace PolicyReplace tab, line feed, and carriage return characters with space character (Unicode character 32).
Substitution GroupElements that are members of a substitution group can be used wherever the head element of the substitution group is referenced.
Substitution Group Exclusions(Applies to element declarations). Prohibits element declarations from nominating themselves as being able to substitute a given element declaration, if they have types that are derived from the original element's type using the specified derivation methods.
Target NamespaceThe target namespace identifies the namespace that components in this schema belongs to. If no target namespace is provided, then the schema components do not belong to any namespace.
