gmt-fork/doc/rst/source/explain_-aspatial_full.rst_

.. _-aspatial_full:

**-a**\ [*col*\ =]\ *name*\ [,\ *...*]
    Control how aspatial data are handled in GMT during input and output.
    *Reading OGR/GMT-formatted files*: To assign certain aspatial data
    items to GMT data columns, give one or more comma-separated
    associations *col*\ =\ *name*, where *name* is the name of an
    aspatial attribute field in a OGR/GMT file and whose value we wish
    to use as data input for column *col*. In addition, to assign an
    aspatial value to non-column data, you may specify *col* as **D**
    for *distance*, **G** for *fill*, **I** for *ID*, **L** for *label*,
    **T** for *text*, **W** for *pen*, and **Z** for *value* [e.g., used
    to look up color via a CPT].  If you skip the leading "*col*\ =" in
    the argument then we supply (and automatically increment) a column
    value starting at 2.  Give just **-a** to select all aspatial items
    to be added to the input record.
    *Writing OGR/GMT-formatted files*: To write OGR/GMT-formatted
    files, give one or more comma-separated associations
    *col*\ =\ *name*\ [:*type*], with an optional data type from DOUBLE,
    FLOAT, INTEGER, CHAR, STRING, DATETIME, or LOGICAL [DOUBLE]. To
    extract information from GMT multisegment headers encoded in the
    **-D**\ *distance*, **-G**\ *fill*, **-I**\ *ID*, **-L**\ *label*,
    **-T**\ *text*, **-W**\ *pen*, or **-Z**\ *value* settings, specify
    *COL* as **D**, **G**, **I**, **L**, **T**, **W** or **Z**,
    respectively; type will be set automatically. Finally, you *must*
    append **+g**\ *geometry*, where *geometry* is either POINT, LINE,
    or POLY. Optionally, prepend **M** for multi-versions of these
    geometries. To force the clipping of features crossing the Dateline,
    use upper-case **+G** instead. See :doc:`/cookbook/ogrgmt-format`
    for details of the OGR/GMT file format.