Thank you very much for your advice.
Phlegm's definition is limited to mucus produced by the respiratory system and particularly expelled by coughing. Phlegm's colours vary from dark yellow and green, dark brown or even dark grey.
Can be a symptom of serious disease such as tuberclosis but can also be a relatively benign symptom of a minor disease such as bronchitis. Coughing up any significant quantity of blood is always serious and if you're experience this, should seek medical attention.