let S be full SubRelStr of L; S is reflexive
let x be object ; RELAT_2:def 1,ORDERS_2:def 2 ( not x in the carrier of S or [x,x] in the InternalRel of S )
assume A1:
x in the carrier of S
; [x,x] in the InternalRel of S
then A2:
[x,x] in [: the carrier of S, the carrier of S:]
by ZFMISC_1:87;
( the carrier of S c= the carrier of L & the InternalRel of L is_reflexive_in the carrier of L )
by Def13, ORDERS_2:def 2;
then A3:
[x,x] in the InternalRel of L
by A1;
the InternalRel of S = the InternalRel of L |_2 the carrier of S
by Def14;
hence
[x,x] in the InternalRel of S
by A2, A3, XBOOLE_0:def 4; verum