if ( zSearch ){
      blob_appendf(&sql,
        " AND (event.comment LIKE '%%%q%%' OR event.brief LIKE '%%%q%%')",
        zSearch, zSearch);
      url_add_parameter(&url, "s", zSearch);
    }
    if( zAfter ){
      while( fossil_isspace(zAfter[0]) ){ zAfter++; }
      if( zAfter[0] ){
        blob_appendf(&sql, 
           " AND event.mtime>=(SELECT julianday(%Q, 'utc'))"
           " ORDER BY event.mtime ASC", zAfter);
        url_add_parameter(&url, "a", zAfter);
        zBefore = 0;
      }else{
        zAfter = 0;
      }
    }else if( zBefore ){
      while( fossil_isspace(zBefore[0]) ){ zBefore++; }
      if( zBefore[0] ){
        blob_appendf(&sql, 
           " AND event.mtime<=(SELECT julianday(%Q, 'utc'))"
           " ORDER BY event.mtime DESC", zBefore);
        url_add_parameter(&url, "b", zBefore);
       }else{
        zBefore = 0;
      }
    }else if( zCirca ){
      while( fossil_isspace(zCirca[0]) ){ zCirca++; }
      if( zCirca[0] ){
        double rCirca = db_double(0.0, "SELECT julianday(%Q, 'utc')", zCirca);
        Blob sql2;
        blob_init(&sql2, blob_str(&sql), -1);
        blob_appendf(&sql2,
            " AND event.mtime<=%f ORDER BY event.mtime DESC LIMIT %d",
            rCirca, (nEntry+1)/2

** Return true if the input string is a date in the ISO 8601 format:
** YYYY-MM-DD.
*/
static int isIsoDate(const char *z){
  return strlen(z)==10
      && z[4]=='-'
      && z[7]=='-'
      && fossil_isdigit(z[0])
      && fossil_isdigit(z[5]);
}

/*
** COMMAND: timeline
**
** Usage: %fossil timeline ?WHEN? ?BASELINE|DATETIME? ?-n N? ?-t TYPE?
**