Significance of red coloured line in source code seen in source v

Hello,
I started using AMAYA and find it very versatile.
When I choose structure view in my document, I find that some lines appear in red.
Does it mean that AMAYA considers these codes  unacceptable?
Those lines of code were entered by using notepad editor.
One example is "bgsound".
Can I continue to enter such codes?
V.DEVARAJAN 
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