cdm/src/main/java/ucar/nc2/iosp/sigmet/SigmetIOServiceProvider.java
public boolean isValidFile(ucar.unidata.io.RandomAccessFile raf) {
    try {
      raf.order(RandomAccessFile.LITTLE_ENDIAN);
      // The first struct in the file is the product_hdr, which will have the
      // standard structure_header, followed by other embedded structures.
      // Each of these structures also have a structure header. To validate
      // the file we check for a product_hdr (by looking for type 27 in the
      // structure_header), then a product_configuration structure (by looking
      // for type 26 in its structure_header), then checking that that
      // the product_configuration does indicate a type of RAW data (type 15)
      raf.seek(0);
      short[] data = new short[13];
      raf.readShort(data, 0, 13);
      return (data[0] == (short) 27 &&
              data[6] == (short) 26 &&
              data[12] ==(short) 15);
    } catch (IOException ioe) {
      System.out.println("In isValidFile(): " + ioe.toString());
      return false;
    }
  }
public boolean isValidFile(ucar.unidata.io.RandomAccessFile raf) {
    try {
      raf.order(RandomAccessFile.LITTLE_ENDIAN);
      // The first struct in the file is the product_hdr, which will have the
      // standard structure_header, followed by other embedded structures.
      // Each of these structures also have a structure header. To validate
      // the file we check for a product_hdr (by looking for type 27 in the
      // structure_header), then a product_configuration structure (by looking
      // for type 26 in its structure_header), then checking that that
      // the product_configuration does indicate a type of RAW data (type 15)
      raf.seek(0);
      short[] data = new short[13];
      raf.readShort(data, 0, 13);
      return (data[0] == (short) 27 &&
              data[6] == (short) 26 &&
              data[12] ==(short) 15);
    } catch (IOException ioe) {
      System.out.println("In isValidFile(): " + ioe.toString());
      return false;
    }
  }
Check if this is a valid SIGMET-IRIS file for this IOServiceProvider.