UL1993 5.4.2怎么理解？

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IEC60335试验指甲

条款：
5 s- X& B3 I& Q) E5.4.2 A device that is constructed so that the alignment with the existing incandescent luminaire or
, ?0 ?1 h) \/ E; {portable luminaire requires an adjustment greater than ±20 degrees shall be provided with adjustment of
+ g9 j/ ]) }7 {% a9 k7 Othe device base with relation to the remainder of the device. Examples include:
a) A rectangular-shaped device in which the device is to be parallel with existing walls when
installed in a ceiling surface luminaire, and
. s( w5 M$ e) F( C( v0 Zb) A device incorporating a ballast compartment or lamp support arms that will in some cases
4 D6 ^9 I5 w" B+ w' k* ^have to be rotated more than 20 degrees to properly clear harps in portable luminaires.
1 S0 |! s$ L# {2 D
该怎么理解？？

powerlg

   没人给解释下？