Output Feature Types

Workspaces generated by FME to read E00 files manipulate and join the features output from the E00 reader to form fully-formed, fully-attributed features with arc, point, polygon, or text geometry. This topic explains each type of output feature and how it is put together.

Each coverage also contains a single polygon feature defining the bounding box of the coverage, and usually a set of four point features representing the TIC points. These features have polygon and point geometries, respectively, with the feature types <prefix>_tic.

Mapping files generated by the FME to write E00 files will only write one type of geometry – point, text, arc, or polygon – to each E00 output file. It will also calculate a bounding box of all features for each E00 file’s BND subfile, and use the corners of this bounding box to define the TIC points.

Arc Features

In ArcInfo, arcs are simply polyline features with attributes to define a topology, as well as user-defined attributes.

The geometry comes from the e00_arcdef features, originating from the ARC subfile and the attributes come from the e00_arc_attr features, originating from the <prefix>.AAT info file. Typically, the attributes defining the topology – left polygon, right polygon, from node, to node – are also defined in the info file, and will appear as attributes on the resulting arc features.

The arc features have a feature type of <prefix>_arc, where <prefix> is the prefix from the info file name. The attributes defined on <prefix>_arc features are summarized in the following table.

Attribute Name	Attribute Value
e00_type	e00_arc
<prefix>-ID	Numerical identifier for arc feature.
<prefix>_	Sequence number of arc feature within the E00 file.
LENGTH	Length of the line, measured in ground units.
FNODE_	Sequence number of starting node of the line.
TNODE_	Sequence number of ending node of the line.
LPOLY_	Sequence number of the polygon that lies to the left of the line when traveling from FNODE to TNODE.
RPOLY_	Sequence number of the polygon that lies to the right of the line when traveling from FNODE to TNODE.

In addition, any other attributes defined in the <prefix>.AAT info file are defined on the <prefix>_arc features generated with this mapping file.

Point Features

Point features are generated when the E00 coverage contains a LAB subfile, but no PAL subfile. In this case, the e00_label features originating from the LAB subfile are joined with the attributes of the e00_point_attr features originating from the <prefix>.PAT info file. The resulting point features have a type of <prefix>_point and the attributes from the following table.

Attribute Name	Attribute Value
e00_type	e00_point
<prefix_ID>	Numerical identifier for point feature.
<prefix>_	Sequence number of the point feature.
PERIMETER	0.0

In addition, any other attributes defined in the <prefix>.PAT info file are defined on the <prefix>_point features generated with this mapping file.

Polygon Features

Polygon features are the most complex of the features created by the generated mapping files. The polygon features result from combining four different types of features output from the E00 reader: e00_arcdef, e00_centroid, e00_polyarc, and e00_poly_attr. A combination of these features is performed as follows.

• The polylines defined by the e00_arcdef features in the ARC subfile form the edges of the polygons. They are combined to form each polygon and its holes, according to the contents of the arcnum{} attributes on each e00_polyarc feature.
• The point geometry from each e00_centroid feature is attached to the corresponding polygon, providing the values for the attributes e00_centroid_x and e00_centroid_y.
• The attributes from the e00_poly_attr features originating in the <prefix>.PAT info file are added to the formed polygon features.

The resulting polygon features have a type of <prefix>_poly and the attributes from the following table.

Attribute Name	Attribute Value
e00_type	e00_poly
<prefix_ID>	Numerical identifier for polygon feature.
<prefix>_	Sequence number of the polygon feature within the E00 file.
e00_centroid_x	X coordinate of polygon’s centroid.
e00_centroid_y	Y coordinate of polygon’s centroid.
PERIMETER	Outer perimeter of polygon.
AREA	Area of the polygon, measured in square ground units.

In addition, any other attributes defined in the <prefix>.PAT info file are defined on the <prefix>_poly features generated with this mapping file.

Text and Textarrow Features

There are two ways text features are formed in the automatically generated mapping files. The first, and most common, is by combining the text geometries from the TX6 or TX7 subfile with the attributes from the <prefix>.TAT<annoLayer> info file. In this case, the resulting text features have a feature type of <prefix>_<annoLayer>_ text, or <prefix>_text if the annotation layer is unnamed. See Text Representation for an explanation of annotation layers.

Some E00 coverages have their annotation defined in a TXT subfile rather than in a TX6 or TX7 subfile. These features are combined with the attributes of the <prefix>.XCODE info file instead of a <prefix>.TAT<annoLayer> subfile, and will always be contained in an unnamed annotation layer.

In either case, text features will have a feature type of <prefix>_text or <prefix>_<annoLayer>_text, depending on whether they are contained in a named annotation layer, and will have the attributes shown in the following table.

Attribute Name	Attribute Value
e00_type	e00_text
<prefix_ID>	Numerical identifier for text feature.
<prefix>_	Sequence number of the text feature within the E00 file.
e00_anno_name	Name of annotation layer containing text feature. This will be “” if it is in an unnamed annotation layer.
e00_anno_id	Sequence number of text feature within its annotation layer. This number starts at 1 for the first feature in each annotation layer and is incremented for every other feature.
e00_rotation	Rotation at which to display text, measured in degrees counterclockwise from horizontal.
e00_text_string	Textual portion of feature.
e00_text_height	Height of text, measured in ground units.
e00_text_level	Number indicating level of text.

In addition, any other attributes defined in the <prefix>.TAT<annoLayer> or <prefix>.XCODE info file are defined on the <prefix>_text features generated with this mapping file.

If the text geometry originates in the TX6 or TX7 subfile – as opposed to the TXT subfile – it might have a separate linear portion that acts as an arrow pointing from the text to another location. These lines are written out as features with a feature type of <prefix>_<annoLayer>_textarrow or <prefix>_textarrow, and attributes e00_anno_name and e00_anno_id which take the same values as the corresponding <prefix>_<annoLayer>_text or <prefix>_text features.

Occasionally, an E00 file will have e00_text features for which there are no corresponding attributes in the info files. In this case, the feature types of the corresponding text features generated are simply text and textarrow.

The E00 writer is not capable of generating TXT features. Text output from the FME takes place with TX6 or TX7 records. See Controlling E00 Output for a description of how geometry is formed on output E00 files.