不可撤销信用证

bù kě chè xiāo xìn yòng zhèng

irrevocable letter of credit

no; not so

(prefix) can; may; able to; -able

chè

to remove; to take away

xiāo

to melt (metal)

xìn

letter

yòng

to use; to make use of; to employ

zhèng

certificate