1. HEC-MetVue requires the PRJ file that is associated with the gridded data file to have a standard well known text (WKT) format. Some ESRI products create by default a PRJ file in a non-WKT format, which is not supported by HEC-MetVue.
  2. The ESRI ASCII Grid File Provider can read or write ASCII files in either TXT or FLT format. However, the file specification for this file type does not have a means to specify additional metadata that HEC-MetVue requires for many of the operations it performs. This is a significant deficiency that limits the usability of ASCII files. The most essential metadata missing form the standard ESRI ASCII Grid file is:
    • Starting date
    • Ending date
    • Measurement units such as inches or mm

Adding additional metadata to the HDR (ASCII FLT) file or ASC (ASCII TXT) file would invalidate the files for other programs that required them since it would not adhere to the specification. The alternative currently supported is to include a 'sidecar' file with the gridded data file.

A sidecar file is simply a file that has the same name as the original file but with a different file extension. ESRI ASCII files already have a sidecar file with a PRJ extension to specify the coordinate reference system.

PRISM data has a sidecar file with an XML extension that has a format that supports the metadata requirements of HEC-MetVue.  The HEC-MetVue ESRI ASCII sidecar file convention was established based on the PRISM metadata sidecar file format. HEC-MetVue requires only a subset of the metadata that the PRISM file specification supports. Below is an XML metadata file created by HEC-MetVue that contains the minimum amount of necessary information.

<?xml version="1.0" encoding="UTF-8"?>
<metadata>
    <idinfo>
        <citation>
            <citeinfo>
                <title>Projected from D:\rainfiles\SWT\07may08.rf</title>
            </citeinfo>
        </citation>
        <timeperd>
            <timeinfo>
                <rngdates>
                    <begdate>20010501</begdate>
                    <begtime>1800</begtime>
                    <enddate>20010502</enddate>
                    <endtime>0000</endtime>
                </rngdates>
            </timeinfo>
        </timeperd>
    </idinfo>
    <eainfo>
        <detailed>
            <attr>
                <attrdomv>
                    <rdom>
                        <attrunit>in</attrunit>
                    </rdom>
                </attrdomv>
            </attr>
        </detailed>
    </eainfo>
</metadata>
XML