Penman was a range of inks made by Parker until about 1999 but it was discontinued due to warranty issues. It was a highly saturated ink sold into a non-specialist mass-market and many users left their pens to dry up only to find they had clogged and were subsequently returned to Parker for service. Parker, therefore, withdrew Penman to remove this warranty problem. See also this thread on Fountain Pen Network
Various substitutes exist for the Penman range as follows:
If you have any more information to add we'd love to hear from you!