I'm experimenting with filters over on-camera flash to better match the ambient light. I'm having good results using CTOs (Colour Temperature Orange filters) with sunlight, for example.

When I'm tasked with shooting indoors, I have an anxiety about confronting older fluorescent lighting that produces a green cast.  It hasn't happened yet, but I'd like to be prepared just in case it does.  So, I'm wondering what is the best general purpose daylight-to-fluorescent flash filter to carry?

Lee offer a "219 Fluorescent green"; however, the description is this: "General tungsten to fluorescent correction for use when fluorescent colour temp is unknown, to provide medium correction." Although, on the Lee website the colour seems to appear as a pale green, in actually the filter is much darker.  I'm assuming this is because the filter has to changing orange tungsten lighting to green fluorescent-coloured light.  So, I expect the 219 will be overkill on a daylight-balanced flash.

From googling I see a "Lee 244 Plus Green" is perhaps a possibility. However, the description on Lee's website — "Used on daylight and tungsten light sources to provide green cast when used in conjunction with discharge lighting. Approximately equivalent to CC30 green camera filter" — makes little sense to me.  There's no mention of using it to balance flash for fluorescent lighting.

Can anyone with experience say, which general-purpose daylight to fluorescent filter, or filters, it'd be wise to carry?

(I'm using digital, so I don't need to worry about a compensating filter over the lens. And, I have a preference for Lee as their filters are available in large sheets, cost next to nothing, weigh even less, and, equally importantly, there's a stockist just around the corner from me!)