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Attribute Node 

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An Attribute Node (and each of its five subtypes: Tag Nodes; Length Nodes; Name Nodes; Value Nodes; Bytes Nodes) are the only grammar nodes that will make the file reader read bytes from the file.

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Attribute name	Description	Possible Values	Mandatory	Default
prefix	If the Attribute Node has a child Name Node, setting this attribute will apply the value of the attribute, followed by an underscore, as a prefix to the name read from the file into the Name Node. This can be useful if the value read can start with a number, or other value which would be invalid when used in a PhixFlow Attribute Expression.	Any string	No	None
discriminator	The discriminator specifies the full value of this field (i.e. the field represented by this Attribute Node) in the file. The discriminator will be converted, according to the type attribute, into the bytes that will be read in the file when this field is found. The discriminator can be used to determine whether optional fields are included in the file.	Any: string, or hex string, e.g A0FF08, if the hexDiscriminator attribute is set to T. Note that the file reader will expect the minimum number of bytes required to hold the value of the discriminator. E.g. if the discriminator is the number 2, the file reader will expect a single byte. If the field uses more than the minimum number of bytes, specify the full value of the discriminator as a hex string. E.g. the discriminator is the number 2, but is represented in the file with 4 bytes, padded with leading 0s; the discriminator would be "00000002".	No	None
hexDiscriminator	Whether the discriminator will be given as a hex string. If the discriminator cannot be specified as an ASCII string then it can be specified as a hex string, where each pair of characters in the string represent a hex digit.	T for true or F for false	No	None
bytes	The number of bytes to be read from the file for this field.	Any of: a number (the number of bytes) a variable name, the variable holding the number of bytes – this variable must have been declared in the variables attribute of this or an ancestor node an Expression inside curly braces which will calculate a whole number. The Expression may refer to Attribute Nodes which have been declared in the scriptVariables attribute of this or an ancestor node. This attribute is not mandatory if any of: the discriminator attribute is set, since the number of bytes can be determined directly from the discriminator this node has a child Value or Bytes Node with bytes attribute set the bits attribute is set this node has a child Length Node this node has a preceding sibling Length Node	No, in certain cases (see notes in Possible Values column) Otherwise yes.	None
bits	The number of bits to be read from the file. This value will take precedence over the number of bytes if both are specified.	Any of: a number (the number of bytes) a variable name, the variable holding the number of bits – this variable must have been declared in the variables attribute of this or an ancestor node an Expression inside curly braces which will calculate a whole number. The Expression may refer to Attribute Nodes which have been declared in the scriptVariables attribute of this or an ancestor node. This attribute is not mandatory if any of: the discriminator attribute is set, since the number of bits can be determined directly from the discriminator this node has a child Value or Bytes Node with bits attribute set the bytes attribute is set this node has a child Length Node this node has a preceding sibling Length Node	No, in certain cases (see notes in Possible Values column) Otherwise yes.	None
type	The type of the field to be read. This attribute dictates how the bytes read from the file will be converted.	Any of: BCD - the field is a binary coded decimal. Commonly used for telephone numbers where each byte contains two numerals, each numeral represented by 4 bits. The result is returned as a string. Integer - a standard integer. String - a string. Float - a floating point number. This type assumes that the number has been encoded as a string which needs to be converted to a float. DateTime - a date and time. This type assumes that the date and time have been encoded as a string which needs to be converted to a date and time. Date - a date. This type assumes that the date has been encoded as a string. The string may include a time component but this will be set to zero (midnight) in the output. BERTag – the field is encoded as an ASN.1 tag in BER format. You do not need to specify a number of bytes for a BERTag field since the length is encoded as part of the data. BERLength - this node is an ASN.1 length value encoded in BER format. You do not need to specify a number of bytes for a BERLength attribute since the length is encoded as part of the data. The type you specify in the grammar is not case sensitive, e.g. it can be "STRING", "String" or "string".	No, if this node has a child Value or Bytes Node, with the attribute type set. Otherwise yes.	None
dateFormat	The format of a date in the file. This should only be set if the type has been set as Date or DateTime. If no date format is specified then the reader will try a variety of possible date formats in turn. It is therefore more efficient to specify a date format, if possible.	A valid date format string. Valid date formats are documented in the PhixFlow online help.	No	None
stringType	This character set to use when converting the bytes read from the file into a string, or converting a discriminator value into the bytes that will be read in the file.	Any string which specifies a valid Java character set, such as UTF8 (or for MariaDB MySQL UTF8mb3).	No	Taken from Grammar Node
byteOrder	The order that bytes will be read from the file when converting into a value.	L (for little endian) or B (for big endian).	No	Taken from Grammar Node
nibbleOrder	The order that nibbles (4 bit blocks) will be read from the file when converting into a value.	L (for little endian) or B (for big endian).	No	Taken from Grammar Node
tagType	If this grammar is for an ASN.1 file and this node is for a tag value – the type of tag. The ASN.1 definition document that describes the file using ASN.1 notation should specify the type of each tag. If not, see the notes at the end of the Tag Node description. This setting dictates how the tag value is translated.	Any of: Universal Application Context Private The tagType you specify in the grammar is not case sensitive, e.g. it can be "CONTEXT", "Context" or "context".	No	Context
berConstruct	If this grammar is for an ASN.1 file and this node is for a tag value - this flag indicates whether the tag is for a constructed value (i.e. a record with sub values) or a simple value. The ASN.1 definition document that describes the file using ASN.1 notation should specify whether this tag is for a construct variable. If not, see the notes at the end of the Tag Node description.	T for true or F for false	No	F

Tag Node 

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The Tag Node is a sub type of the Attribute Node. It has the same attributes as the Attribute Node, and will read bytes from the file to calculate a tag value.

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Code Block
language xml
<Tag name="hexTag" type="Integer" discriminator="A5" hexDiscriminator="T"/>

Length Node 

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The Length Node is a sub type of the Attribute Node. It has the same attributes as the Attribute Node, and will read bytes from the file to obtain a length value.

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If a Length Node sets the length on a Sequence or Record Node, then the length determines how many bytes are expected across all remaining child Attribute Nodes of that Record or Sequence Node after the Length Node (i.e. not including any child Attribute Nodes before the Length Node). See Control Nodes Attributes.

Name Node 

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The Name Node is a sub type of the Attribute Node. It has the same attributes as the Attribute Node, and will read bytes from the file to obtain a name. 

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If more than one Name Node is specified then the second and subsequent Name Nodes will append an underscore, followed by the value of the Name Node, to the end of the name created by the first Name Node.

Value Node 

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The Value Node is a sub type of the Attribute Node. It has the same attributes as the Attribute Node, and will read bytes from the file to calculate a value.

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If the bytes, bits, type, stringType, byteOrder and nibbleOrder attributes are not set on a Value Node then the corresponding attributes on the most immediate Attribute Node ancestor will apply. Just as for Tag Nodes inheriting discriminators, this is useful when creating reusable templates (see Tag Node). Rather than specifying these attributes in the template, they can be set on the Attribute Nodes that use the template. These attribute values will be inherited by the child nodes copied from the template. In this way the same template can be used for a range of Integer, String or BCD attributes with different byte, nibbleOrder, etc. attributes.

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The same technique could be used to convert strings to Integers, Floats, Dates or DateTimes.

Bytes Node 

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The Bytes Node is a sub type of the Attribute Node. It has the same attributes as the Attribute Node, and will read bytes from the file to obtain a value. 

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