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       COMMAND

       ffffiiiillllllll ---- ffffiiiillllllll vvvvooooiiiiddddssss bbbbyyyy iiiinnnntttteeeerrrrppppoooollllaaaattttiiiioooonnnn oooorrrr eeeexxxxttttrrrraaaappppoooollllaaaattttiiiioooonnnn

       USAGE

       ffffiiiillllllll [----lllliiiihhhhttttggggssssvvvv][_d_e_l_t_a]

       ----llll    Extrapolate terminal points to the lower latitude or
             longitude range boundary.

       ----hhhh    Extrapolate terminal points to higher latitude or
             longitude range boundary.

       ----iiii    Interpolate linearly across interior void intervals,
             the default.

       ----tttt    Interpolate/extrapolate along latitudes.

       ----gggg    Interpolate/extrapolate along longitudes.

       ----ssss    Add _d_e_l_t_a to filled values. _S_t_a_n_d_o_u_t mode.

       ----vvvv    Invert sign of extrapolated radii bridging interior
             voids. _V_o_i_d_m_a_r_k mode.

       ----uuuu    Fill only voids with uuuunnnniiiitttt length.

       DESCRIPTION

       The ffffiiiillllllll command provides a means for filling VVVVOOOOIIIIDDDD data
       points and intervals falling into three general categories.
       The image may contain intervals which are completely void
       above some latitude on a given longitude of the image.
       Conversely, there may be intervals which are completely void
       below some latitude on a particular longitude of the image.
       Finally, there may be points and intervals containing void
       values interspersed at various latitudes interior to other
       valid data points.

       Since you may have reason to ffffiiiillllllll selected categories and
       combinations thereof at the exclusion of others, the
       arguments of the ffffiiiillllllll command are provided to accomplish
       such ends.  The ----llll , ----hhhh and ----iiii arguments specify the void
       category to be filled, the ----tttt and ----gggg arguments specify the
       direction in which the void filling process is to be
       accomplished.  The ----ssss argument along with _v_a_l_u_e in microns
       highlights interior void regions by adding _v_a_l_u_e to the
       interpolated value.  This feature may be useful, for
       example, in highlighting light absorbing scribe marks made
       on subjects.  Such marks can produce an intentional pattern











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       of voids demarking certain reference features.

       In certain applications users may need to have a means of
       knowing which radius values of a filled image are
       extrapolated versus measured.  The ----vvvv argument forces an
       inversion of the sign of extrapolated radii so that all such
       originally-void points in positive regions of the image may
       be located by testing for negative radii. These points may
       then be treated separately and/or differently as deemed
       approptiate.

       CAVEATS

       Attempts to fill interior intervals may produce error
       messages indicating an inability to compute values.  There
       are generally two ways in which this might occur.  One such
       failure occurs when you invoke the longitudinal void-filling
       mode when the current longitude range includes longitudes
       containing only voids.  Similarly, if latitudinal void-
       filling is invoked for an image whose latitude range
       includes latitudes which are entirely void, no basis for
       assignment of replacement values is available and that
       latitude is skipped.

       In either instance, lacking a rationale for assignment of
       radius values, these longitudes are simply skipped and
       indicated by a message.
































