Gene, let me be more specific. Since you wanted to know the definition, you can get it at
http://pesaraonline.net/1stschedule.htm The part pertaining to manual labour is as follow:
"2. Any person who, irrespective of the amount of wages he earns in a month, has entered into a contract of service with an employer in pursuance of which
(1) he is engaged in manual labour including such labour as an artisan or apprentice;
Provided that where a person is employed by one employer partly in manual labour and partly in some other capacity such person shall not be deemed to be performing manual labour unless the time during which he is required to perform manual labour in any one wage period exceeds one-half of the total time during which he is required to work to such wage period;
(2) he is engaged in the operation or maintenance of any mechanically propelled vehicle operated for the transport of passengers or goods or for reward or for commercial purposes;
(3) he supervises or oversees other employees engaged in manual labour employed by the same employer in and throughout the performance of their work; "
On the question of "quality control", the answer cannot be a simple yes or no. Quality control is quite a varied field. The quality control for each product may required different know-how or knowledge. An employee who is engaged just to check for cracks or defects in a product may not required special knowledge or training whereas one who is required to check for defects in some high-tech products may required special training or knowledge. So, one may say the former is manual labour while the later is not. It is all based on facts and arguable