COPY command with blank incoming values

Does COPY require values for each column even though the database field
is not set to NOT NULL? I did a COPY TO first to line up the data and
then COPY FROM a tab delimited file. Here are the first 5 fields in the
first line of the incoming file (omit the quotes, I put them there to
see where the start and end of the line is), you should find 3 tabs
after the second '1':

'1    1            '

I have a table with this structure below and when trying to COPY the tab
separated file into the table, it says it expects and Integer for the
field that does not require a value:

CREATE TABLE "public"."tblxrf" (
  "xrf_id" SERIAL,
  "seq_no" SMALLINT NOT NULL,
  "xlno" SMALLINT,
  "site" INTEGER,
  "insp" DOUBLE PRECISION,
  "flr" VARCHAR(10),
  "side" VARCHAR(25),
  "room" VARCHAR(25),
  "source" VARCHAR(50),
  "sub" VARCHAR(50),
  "feat" VARCHAR(50),
  "cnd" VARCHAR(25),
  "clr" VARCHAR(25),
  "note" VARCHAR(255),
  "ssec" DOUBLE PRECISION,
  "date/time" TIMESTAMP WITHOUT TIME ZONE,
  "cycle" VARCHAR(25),
  "di" DOUBLE PRECISION,
  "result" CHAR(3),
  "pbl" NUMERIC(3,2),
  "pbl_error" NUMERIC(3,2),
  "pbk " NUMERIC(3,2),
  "pbk_error" NUMERIC(3,2),
  "pbc " NUMERIC(3,2),
  "pbc_error" NUMERIC(3,2),
  "res " VARCHAR(25),
  "res_error" VARCHAR(25),
  CONSTRAINT "tblxrf_pkey" PRIMARY KEY("xrf_id")
) WITH OIDS;

ohc=# copy tblxrf from '/home/admin/xrf-all.tab';
ERROR:  invalid input syntax for integer: ""
CONTEXT:  COPY tblxrf, line 1, column xlno: ""

--
Robert